Without documenting the issues properly, there is no "more reliable build coming out soon" (in particular, not regarding the above issues).
Why? Because nobody else reported anything like this on the recent builds.
In particular, I'm
waiting for feedback on the lua_fix builds, to decide whether to merge them into mainline, or wait. Before your report, I would have assumed things are fine on 600D, fix the remaining nitpicks for other models (not related to any of your issues), and merge lua_fix into mainline (without being able to address your issues). Now I'm confused.
Without seeing the error, and without knowing what modules you were trying to load, what settings you have changed from default, and what additional files you have used (such as extra modules or custom scripts - you mentioned scripts), I'm unable to answer (and I doubt anyone else is). It might be user error or it might be a real issue - I have no idea.
To create a more reliable build, first I need to know the issues with the current build and how to reproduce these errors. From fuzzy reports (or worse, from lack of reports), I'm unable to draw any meaningful conclusions, so if you just wait, the next build will either be mostly the same as the current one (with just minor fixes on other models) or it may have untested stuff that breaks even more functionality (as I may assume things are working fine, and go ahead and merge some experimental branches into mainline without knowing how they actually work on 600D).
I can run
some limited tests in QEMU, but as emulation doesn't currently cover LiveView or photo capture, the tests I'm able to run are quite basic (whether you can navigate ML menu, whether you can load modules/scripts, whether we are correctly reserving memory from Canon firmware and similar stuff). Most of the "interesting" features are much harder to test in the emulator.
The above applies to any other camera model, not just 600D.
https://www.chiark.greenend.org.uk/~sgtatham/bugs.html