It makes me very sad to say, that YES you can get banned for using an addon, and it is not predictable whether you will or not. Case in point is the banning of players for an API call that AV multiqueue addons Lazypig and Stinkyqueue use. Despite being completely blizzlike, some players were banned for using them - originally permanently - and then reduced to 10 days.
The GM in question didn't know that the addon existed or how it worked, and accused the players of creating it, despite the fact that it existed in vanilla. But because they banned the use of an API call that had been there forever and in vanilla, the implication is that ANY addon, whatsoever, might end up getting you banned. You roll the dice using them.
I requested that a GM or Admin explicitly identify what API calls are safe. Of course i got no response.
Edits: I rewrote a lot of this to be a little less over the top and a little less repetitive. I should know better than to post while smashed!