I guess nowadays I either try to watch skating sans commentary or watch it in other languages so it's definitely possible there are great commentators out there that I have never listened to. I guess PJ Kwong is probably one. You can tell that she really cares about skating and she definitely does her research.
It always shocks me how Chris Howarth and Nicky Slater - both of whom work in skating as coaches and choreographers - often lack knowledge of the IJS rules and fail to notice a lot of errors that should be apparent to somebody who's a skating insider. They also don't seem to do much background research on skaters and seem to know less about them than many skating fans do.
P.S. Not everybody will know everything, it's only natural. When you don't know about something simply don't mention it, instead of pretending that you do know it and talk bullshit...
The Polish Eurosport commentator is actually very decent. He knows what he's talking about, he points out a lot of details and gives some interesting background info as well (he won't for example say 'fantastic' when a pair team does a triple twist where a lady collapses onto the man instead of being caught by the waist and put down - which Chris/Simon/Nicky do regularly). I disagree with him a lot but he's honest and makes clear arguments for why he thinks a certain way and you can take it or leave it.