Still works for me, a 5 star rating shows up at the top of the screen once the match starts. It might not show up if you set "Ratings" in display options to "Invisible". Also check the console window once the game opens up, if the mod properly loads in it should say
"[Info : BepInEx] Loading [CareerMatchRatings 1.0.1]"
"[Info :CareerMatchRatings] Loaded CareerMatchRatings!"

does this still work? I can't tell if it's just me but it's not showing up in my career.

I'm not sure but I believe it's visual only and doesn't have any real gameplay impact

Does this affect company's ratings in career mode? For example, I want to be a skillful and entertaining wrestler in career mode, rather than someone who bulldozes his opponents, does this work for my character type?

Everything is explained in the game manual, check "Entertainment" on page 13: http://mdickie.com/guides/wempire.pdf

Could we possibly get a short explanation of the icons and how they are triggered and a basic idea of what events raise the overall quality

A mod I've long since dreamt of for this game