bullet point #2 fails more than half of the time for me.

What I found works for me is… well I’ll just repost my previous advice:

if anyone is struggling with installing 3rd party mods and such in Proton, try starting your installation process from ConEmu (ConEmu64.exe) (It’s a simple, open-source, portable terminal emulator for Windows) instead of pointing the Non-steam Games wizard at each installation and gaming exe individually.

I originally tried to do this with the explorer.exe built into Wine, but getting that thing to launch is a pain.

for example a lot of Windows programs will have you download an .exe that installs the program, then you need to run a different .exe to actually run the program. Steam’s non-steam game wizard in combination with Proton gets confused by this and runs the two .exe’s in separate environments, screwing with any attempts to install a mod or install the app itself.