Ah, those are good points and it would make it “murky” about Cassian’s “secret” orders. What would be the point of those orders if the earlier scene at the briefing room was just about finding the pilot. I also get what you mean with Jynn’s role and it does make some sense. There would be a disconnect with the “kill orders” if there was nothing officially or unofficially talked about finding Galen.
SO I would be ok with not going that route now for the sake of the “secret kill orders” since that change in itself I think adds plenty of benefits.
It could simply be explained as Draven saying, find the pilot and bring him to us so we can find and eliminate Erso. Returning the Pilot would go along with that narrative. Their learning of Galen being on Eadu then prompts Cassian to update the mission status and ask if they should go to Eadu to finish the mission. Draven says proceed and stick to his orders. No continuity issues, imo. Especially due to the fact that the order is never explicitly heard from Draven.