I noticed that some games switched from Dosbox SVN to Dosbox Staging for better performance. Inside the game folder they have their own custom dosbox config file. Eg Stonekeep.conf. However the issue is that they are using Staging's conf file in the users folder too, instead of just the one inside the game folder.

As a result many do not launch as they require the default dosbox staging configuration in users folder. If you make any changes in that conf file, chances are games will not run.

Only solution is to remove dosbox staging conf file from users folder, launch the game once and then the default dosbox staging conf file will be created. Copy the file from users folder to the game folder and then restore your own custom config in users folder.

This way game will launch, you can tweak that conf for the game and you can tweak user's folder dosbox conf for your own custom settings for non-GOG games.

I'd suggest to make the games use de facto the dosbox staging conf file inside the game folder, instead of just one default file in users folder.