– The Witcher: Enhanced Edition runs great, but crashes the whole system as soon as I try to save the game.
I would suggest checking that you have all of Wine's dependencies first, as this does not happen on the systems I use for testing (I have 3 - my main system with Ryzen 1700 + RX 480 using the open drivers, my old system with i7-2600k + GTX750Ti using the proprietary drivers, and an i3-6100 system with integrated graphics). All run Mint 18.x (old system Mint 18, others 18.2), which is also based on Ubuntu 16.04
Are you sure it crashes the whole system/are you able to log in via a TTY (press Ctrl+Alt+F1)? If you can, then cd to the game directory and run: ./start.sh run="wineserver -k"
then logout go back to your desktop session (usually Ctrl+Alt+F8 or F7). Alternatively, if you have xkill installed then you can set a shortcut key combo to run it and then when it freezes just press they key combo and then left click.
– Fallout 3/New Vegas: The install scripts are for the US/English versions — what‘s the best way to adapt your scripts to other languages, e.g. German?
In my experience there's quite a lot of variation with how GOG installers are packaged (even between updates to the same release), so it probably wouldn't be as simple as just modifying it to use the different installer files & would require examining how the installers are packed and creating a new build script for them accordingly. Registry entries would also need to be changed to suit the different language release.