Thanks for the update!

The issue with the path was most likely due to find resolving to C:\windows\system32\find.exe instead of GNU find. Instead of modifying the MSYS2 enlistment (and possibly leaving it in a bad state if the build fails!) I changed the portfile to insert the path in the middle.

Could you comment on why you chose to do several individual calls to bash instead of using a separate script (like in ffmpeg)?

Nothing special, just thought the logs will be a little cleaner this way.