Can I mention one more bug if it doesn't disturb your work?
In the main screen I go to studio, manage midi devices, banks, import, change file type to sf2, click to open a sf2 file and Rosegarden freezes.
(I waited +/- 15 minutes trying to import the banks from the free soudfont Merlin Gold, nothing happened and I had to kill Rosegarden because it didn't respond to close buttons too. I also tested with other soundfonts.)
If you find it interesting to reproduce and do research on this is the way I did.