In colloquial French, the French you hear spoken everywhere in informal settings in all phases of everyday life, you will hear on being used as "we". It is not borderline bad grammar anymore. It might have been years ago, but now it has been assimilated into normal everyday spoken French.

One thought about your language proficiency not matching your level determined by kwiziq. You can always choose to do exercises from a more advanced level. Just put them into your notebook. You can also do reading and listening exercises from a more advanced level. Sometimes, however, it's good to refresh older knowledge that hasn't been used. Happened to me, too. I swallowed my pride and decided to do them anyway. In the process, I picked up a few things I didn't know. It certainly didn't hurt me.