Square Enix game launcher is very unstable and freezes most of the times. Had to set the screen resolution via the game settings file

The game runs with default Proton, but only on 768x640 screen resolution. Higher resolutions or disabling windowed mode leads to the game crashing after pressing Play. The Square Enix launcher is very unstable after starting the game from Steam. In order to try out different screen resolutions I had to change the settings in the Settings.ini, found in ~/.steam/steam/steamapps/common/FINAL FANTASY IX.

I also tried out GE-Proton9-7, which leads to an instant crash skipping the Game launcher.

Only played the first scene, unfortunately it is not really fun with that small window. As other people have more success I assume my system may be responsible.