COUNTIFS: Column Formula pulling from 2 Columns on 2 Sheets

Hello!

I've built some COUNTIFS in the past and I've always struggled, but I've also always managed to get it in the end. I'm trying to build a column formula that pulls data from 4 different columns between two different sheets. What I've come up with so far is coming back with UNPARSEABLE.

=COUNTIFS({Reviewer 1}, Associate@row), OR(COUNTIFS({Project Reviews Range 2}, Associate@row)

^I tested just the first half and it pulled the correct amount/updated when I added more as it should, but the second I try adding the OR option, it seems to not like it. I've tried with with both a new COUNTIFS and without. There was one way that it seemed like it was working, but the information from the 2nd half was overriding all the information from the 1st half instead of adding to it. If anybody has any clue as to what I'm doing wrong or could throw out suggestions, that would be great! Especially given that I still have to add another entire part to this to count the other sheet on top of this as well.

Thanks in advance!