I did encounter one bug but it was an engine bug. If I put the game in fullscreen mode it would always go to my monitor on the right not my left monitor regardless of which was set as primary. This was a bug with the Ren’Py engine not specific to The Last Birdling as it happened on every Ren’Py game I tried. It was fixed with the most recent version of Ren’Py (7.2.1). Just letting you know, not sure if it is feasible for you to upgrade the engine version the game is using.