Can I Change Aperture w/o Chipped Lens?

[InACanoe]

Hi, this is a question stemming from an existing thread in /r/askphotography, https://www.reddit.com/r/AskPhotography/comments/p2db69/failure_to_preview_brightness_correctly_canon_eos/

My camera is a Canon EOS Rebel T4i
On the latest nightly build (from 2018) https://builds.magiclantern.fm/650D-104.html
And a non-chipped lens adapter for an analog lens

What happens, is in every mode on my camera except for Av, Portrait, (Macro is maybe 1 stop away from being accurate), Sports, Night Portrait, Handheld Night Scene (In dark areas), and HDR Backlight Control..

What I see in Live View is darker than the photo the camera will actually take, by about 5-6 stops.
This makes focusing via the live view very difficult, because it's way too dark. And using M mode while everything is too dark is difficult to say the least.
What's also interesting is that the exposure level bar always shows accurately in M mode, so even if the preview is too dark, I can still accurately judge the photo's brightness with just the exposure level bar. I always view-find with the aperture wide open (lens claims 3.9).


Is there some way to override the aperture settings, even if a non-chipped lens/adapter is being used?
I found this page, https://wiki.magiclantern.fm/camera_help that says you can't, but wanted a second opinion. I checked and it says the same on my camera, maybe there's a way around that?

All the best,
    InACanoe