I say assume it's right because I've adjusted it multiple times (following park tools guide) thinking that might have been the cause but as far as I know, everything is properly tuned.

I did not think to check the cable for dirt or grime so I'll do that now.

As for the trim, it is a Microshift 9 speed shifter, I have no clue which way the trim is. It takes two clicks to go from the small chainring to the middle, so is that the trim?