@ Barra ..curious what the issue with the encoder Push buttons is ? they should act like any normal button eg a tac switch , at least that was my thinking / understanding.
set the filtering to 12 or 14 and see if you still get the Trim Pots spiking , it sounds like you have one that is bad , sometimes you can open the pot and clean it and it will work better , lots of info online how to do that , like this old post at Cougar World, the FLCS pots are very easy to open actually , not sure about what you have...