Pretty sure the 412 doesn't recognise pilot input in ATT, same as 109. I certainly remember the beeper trim being too slow for precise hover work and the force trim release causing way too much stick jump.
In ATT mode, you can roll into a turn against spring pressure and then release and it will roll you out again - you can beeper trim it into the turn and it will stay there. I don't understand what you mean by 'doesn't recognise pilot input in ATT'.
I certainly remember the beeper trim being too slow for precise hover work
That's why you would use SAS mode for that.
If you use the stick trim properly - ie press it before moving the cyclic - you don't get the stick jump. Keep ATT mode for the cruise and IFR.