Interesting, I have a Roland S-330 from the late 1980s and my main concern getting it was the floppy drive viability. It didn’t occur to me that the mouse would be difficult.
You probably already know this stuff or have decided against it for authenticity or whatever, but just in case, you can use some of the Gotek USB flash drive floppy disk emulators:
Nexxxeh|11 months ago
https://github.com/keirf/FlashFloppy/wiki/Host-Platforms#rol...
And this may or may not be out of date, but may still be useful:
https://llamamusic.com/s50s550/FlashFloppy_GOTEK.html