Forums Scripts & Popups check if user isop

Afaik mIRC is parsing the raw like you guessed, and does a /names #chan on join to get not only the nicks but their channel status as well.

A check for "isop" is sufficient to check for nick x having op on chan y.
To track "mode changes" of modes that may vary depending on the ircd used, like +a = "protect", you'd have to parse the "on rawmode" event on your own. In addition, you may compare a $nick(y,x).pnick to $prefix to $nickmode.