I have flown Efis 84 C90/B200 and for the last 10yrs only Proline 21 ships.
None of this Ac, appr. 5 C90 - 4 B200 - one 350 and one 300 would trim Rudder by itself. The Rudder trimwheel stays where it is. We trimmed even with AP engaged, to get the ball centred. On AP with Engaged YD it would help to slighly press one pedal to help the trim work against the YD. It would do without but that takes way longer.
I presume if the cabe breakes, the Trimwheel will move loosely and of course the tab only moves in one direction. But iam not an engeneer, just a Driver.