I don’t even like connecting to the net with pirated games. Always feel I’ll get banned and I used game piracy to test drive them.
Pirated games wouldn't be associated with your Steam account so I don't think you would be banned.
Even using the Steam API I don't think you would unless you were sharing it openly or were making an obscene amount of requests.
That said I don't know a ton about online fixes or using CreamAPI to unlock DLC for games you own so maybe it would be possible to get banned in that regard.