It does work, but its extremely slow. Even on Rpi2 with adjustments to the makefiles to build for arm7, you can’t even get a full speed A500 out of it.
FS-uae uses the modern WinUAE cores which are focused on acccuracy. Unfortunatley this makes it a lot more CPU intensive than uae4all so i cant imagine this ever working smoothly on the PI.
Uae4all2s menu has been built for touchscreen/android (and works well for that platform) No work has gone into adapting this to raspberry, hence a lot of the menu options not working.
There is a fork of uae4all2 by chips that allows setting options from the commandline along with improvements to graphics handling. Unfortunately this is not the version used in retropie right now.