I've been pushing several users into doing tests on these firmware updates and since nobody seems to be responding on the 500D.112 and I happened to have my hands on one I guess it is up to me to run these tests.
Made a lua_fix build for the new firmware and these tests failed:
test_keys
test_lv failed
test_lens_focus
test_camera_exposure
All the others were fine. Of course the first thing I ask testers to do on a firmware update is to regress to the previous firmware version to see if this is a new issue or inherited from the previous version. Same issues on 1.1.1.
The lens focus test is interesting because it the lens will go from infinity to closest distance before failing. If the lens is focused at the closest setting to begin with it will fail right away. The 500D might be a camera that the lens can only be controlled by lua when in LiveView so I hacked up the script a bit, set the camera in LiveView and it completed this test using an old 28-105mm lens:
===============================================================================
ML/SCRIPTS/API_TEST.LUA - 2018-5-2 19:05:13
===============================================================================
Module tests...
Testing lens focus functionality...
Focus distance: 655350
Focusing backward...
Focus distance: 655350
Focus motor position: 0
Focusing forward with step size 3, wait=true...
...
Focus distance: 470
Focus motor position: -1974
Focusing backward with step size 3, wait=true...
...
Focus distance: 655350
Focus motor position: -69
Focus range: 520 steps forward, 366 steps backward.
Motor steps: 1974 forward, 1905 backward, 69 lost.
Focusing forward with step size 3, wait=false...
....................................
Focus distance: 470
Focus motor position: -1974
Focusing backward with step size 3, wait=false...
......................................
Focus distance: 655350
Focus motor position: -77
Focus range: 36 steps forward, 38 steps backward.
Motor steps: 1905 forward, 1897 backward, 8 lost.
Focusing forward with step size 2, wait=true...
...
Focus distance: 470
Focus motor position: -1967
Focusing backward with step size 2, wait=true...
...
Focus distance: 655350
Focus motor position: -69
Focus range: 840 steps forward, 770 steps backward.
Motor steps: 1890 forward, 1898 backward, 8 lost.
Focusing forward with step size 2, wait=false...
...
Focus distance: 470
Focus motor position: -1971
Focusing backward with step size 2, wait=false...
...
Focus distance: 655350
Focus motor position: -76
Focus range: 168 steps forward, 161 steps backward.
Motor steps: 1902 forward, 1895 backward, 7 lost.
Focusing forward with step size 1, wait=true...
...
Focus distance: 470
Focus motor position: -1983
Focusing backward with step size 1, wait=true...
...
Focus distance: 655350
Focus motor position: -106
Focus range: 1737 steps forward, 1477 steps backward.
Motor steps: 1907 forward, 1877 backward, 30 lost.
Focusing forward with step size 1, wait=false...
...
Focus distance: 470
Focus motor position: -2002
Focusing backward with step size 1, wait=false...
...
Focus distance: 655350
Focus motor position: -108
Focus range: 462 steps forward, 444 steps backward.
Motor steps: 1896 forward, 1894 backward, 2 lost.
Focus test completed.
Done!
The only key that test_keys is checking for is the half-shutter press.
platform/500D.111/gui.h
#define BGMT_PRESS_HALFSHUTTER 0x23
Checking this against the results of Debug -> Show GUI events

Well 0x3f definitely didn't work and neither did 0x24 so maybe this is somewhere else?
The test_lv does put the camera in LiveView then dies.
===============================================================================
ML/SCRIPTS/API_TEST.LUA - 2018-5-2 19:55:31
===============================================================================
Module tests...
Testing module 'lv'...
Starting LiveView...
Looks like there's some doubt in the code.
platform/500D.111/gui.h
#define BGMT_LV 0xf // idk?
Finally, test_camera_exposure starts off well outside LiveView but dies when trying to set ISO values.
===============================================================================
ML/SCRIPTS/API_TEST.LUA - 2018-5-2 19:58:31
===============================================================================
Module tests...
Testing exposure settings...
Camera : Canon EOS REBEL T1i (500D) 1.1.2
Lens : EF28-105mm f/3.5-4.5 USM
Shoot mode: 3
Shutter : Ç125 (raw 112, 0.007812s, 8ms, apex 7.)
Aperture : Å5.6 (raw 48, f/5.6, apex 5.)
Av range : Å3.5..Å22 (raw 37..80, f/3.5..f/22.6, apex 3.625..9.)
ISO : ÄAuto (raw 0, 0, apex 0)
EC : 0.0 (raw 0, 0 EV)
Flash EC : 0.0 (raw 0, 0 EV)
Setting shutter to random values...
Setting ISO to random values...
However, if the exposure test is done in LiveView:
===============================================================================
ML/SCRIPTS/API_TEST.LUA - 2018-5-2 20:15:51
===============================================================================
Module tests...
Testing exposure settings...
Camera : Canon EOS REBEL T1i (500D) 1.1.2
Lens : EF28-105mm f/3.5-4.5 USM
Shoot mode: 3
Shutter : Ç125 (raw 112, 0.007812s, 8ms, apex 7.)
Aperture : Å5.6 (raw 48, f/5.6, apex 5.)
Av range : Å3.5..Å22 (raw 37..80, f/3.5..f/22.6, apex 3.625..9.)
ISO : Ä3200 (raw 112, 3200, apex 10.)
EC : 0.0 (raw 0, 0 EV)
Flash EC : 0.0 (raw 0, 0 EV)
Setting shutter to random values...
Error: shutter set to value=0.009291, got 0.010132s, expected 0.009291s
Error: shutter set to value=0.009291, got 10ms, expected 9ms
Error: shutter set to value=0.009291, got Tv6.625, expected Tv6.75
Error: shutter set to value=0.009291, got 109, expected 110 (raw)
Error: shutter 0.010132s != Tv6.625, expected 6.75
Error: shutter 5.187358s != Tv-2.375, expected -2.25
Error: shutter set to value=0.000581, got 142, expected 141 (raw)
Error: shutter set to ms=115, got 0.125s, expected 0.114626s
Error: shutter set to ms=115, got 125ms, expected 115ms
Error: shutter set to ms=115, got Tv3., expected Tv3.125
Error: shutter set to ms=115, got 80, expected 81 (raw)
Error: shutter set to value=14.672065, got 16s, expected 14.672065s
Error: shutter set to value=14.672065, got 16000ms, expected 14672ms
Error: shutter set to value=14.672065, got Tv-4., expected Tv-3.875
Error: shutter set to value=14.672065, got 24, expected 25 (raw)
Error: shutter set to value=32, got Tv-5., expected Tv-4.875
Error: shutter set to ms=7336, got 8.s, expected 7.336032s
Error: shutter set to ms=7336, got 8000ms, expected 7336ms
Error: shutter set to ms=7336, got Tv-3., expected Tv-2.875
Error: shutter set to ms=7336, got 32, expected 33 (raw)
Error: shutter set to value=0.028656, got Tv5., expected Tv5.125
Error: shutter set to value=0.028656, got 96, expected 97 (raw)
Error: shutter set to value=3.668016, got 4.s, expected 3.668016s
Error: shutter set to value=3.668016, got 4000ms, expected 3668ms
Error: shutter set to value=3.668016, got Tv-2., expected Tv-1.875
Error: shutter set to value=3.668016, got 40, expected 41 (raw)
Error: shutter set to value=19.027313, got 20.749433s, expected 19.027313s
Error: shutter set to value=19.027313, got 20749ms, expected 19027ms
Error: shutter set to value=19.027313, got Tv-4.375, expected Tv-4.25
Error: shutter set to value=19.027313, got 21, expected 22 (raw)
Error: shutter set to value=0.000488, got Tv11.000001, expected Tv11.125001
Error: shutter set to value=0.000448, got 145, expected 144 (raw)
Error: shutter set to value=19.027313, got 20.749433s, expected 19.027313s
Error: shutter set to value=19.027313, got 20749ms, expected 19027ms
Error: shutter set to value=19.027313, got Tv-4.375, expected Tv-4.25
Error: shutter set to value=19.027313, got 21, expected 22 (raw)
Error: shutter set to value=3.668016, got 4.s, expected 3.668016s
Error: shutter set to value=3.668016, got 4000ms, expected 3668ms
Error: shutter set to value=3.668016, got Tv-2., expected Tv-1.875
Error: shutter set to value=3.668016, got 40, expected 41 (raw)
Error: shutter set to value=0.007164, got 0.007812s, expected 0.007164s
Error: shutter set to value=0.007164, got 8ms, expected 7ms
Error: shutter set to value=0.007164, got Tv7., expected Tv7.125
Error: shutter set to value=0.007164, got 112, expected 113 (raw)
Error: shutter set to value=29.344129, got 29344ms, expected 32000ms
Error: shutter set to value=29.344129, got 17, expected 16 (raw)
Error: shutter set to value=29.344129, got 17, expected 16 (raw)
Setting ISO to random values...
And once again dies when setting ISO values.