Yeah, this is the thing:
First, I installed the games (including ToSC and ToB), ran bg1_tutu.exe (saying no to keeping some rare sounds, and no to changing NPC classes to kits), then ran setup_tutufix.exe (saying Y to everything), and then Setup-tutu_tweaks.exe (saying Y to most, N to some). Then I ran the game, and it crashed when doing said things.
Then, I ran bg1tutu_restore.exe and bg1_tutu.exe right again. I did not touch tutufix or tutu-tweaks (don't know if they're uninstalled along with bgtutu or not). After that, everything worked fine, but I didn't have the tweaks I selected.
Then I tried running tutufix again, and it asked if I wanted to install, reinstall (indicating the fixes were not uninstalled when running tutu_restore), say yes, say no or quit. I chose to reinstall everything, and then ran the game. Hello crashes.
So now I'm running the game without the tweaks I selected, and perhaps without the fixes, I'm not sure. It's fine, but I'd still like to track down this bug.
And thanks.