Are we to assume that Covenant AI, if any, also joined Cortana at the end of Halo 5: Guardians alongside humanities? We know that at least some exist in Halo lore due to Cortana encountering one (or several) on board the Covenant Command Platfoem Unyielding Hierophant. If the crew on the UNSC Infinity are actively fighting against Cortana and her AI then one can assume that they would encounter them somewhere down the road.
Probably not because the Covenant purposefully only made “dumb” AI because the prophets knew about mendicant bias in some fashion and knew how it went rogue on the forerunners (at least I’m pretty sure that’s the reason).
Dumb AI only serve specific functions with limited free thought and I believe they have no chance of going rampant. They will just get normal wear and tear like any other piece of tech.