Diki I never actually played an FP-50 or FP-80. But it's apparent from the owner's manual that these style pianos have Bass Inv implemented as a momentary function, optionally assignable to one of the three piano pedals. So it certainly can be done and has been done with professional results.

The FP-50/80 are contemporary with the BK-series and may share some of the OS. The BK acknowledges the status of Bass Inv at the same time it recognizes the chord. If you do anything with the pedal after that, it doesn't have any effect until you play the next chord. There are no weird portamento effects, and it doesn't sound like the bass player swallowed a clam. It works seamlessly and as expected.

Depending on the mix of chords in the song, turning bass inv on and off in real time can save big "jumps" of the left hand, or wide finger spans such as would needed to play Cmaj7 with root bass, etc.

Yamaha knows this too. That's part of the justification for developing their flagship "AI Fingered" mode, which gives an on-bass chord for two-note fingering, and the root bass when three or more notes are played. This approach introdcues its own well-known set of problems. For most of the songs I play, Roland's chord intelligence -- with momentary bass inversion controlled by a foot pedal -- is an easier and more consistent approach. I offer the details here so that others may consider it, and adopt it for themselves.