Why do you want to put in work if you don’t even know whether or how much of the flakes will remain?
Legitimate question Well, half will definitely remain. So something definitely has to be done and I prefer to inform myself a bit earlier. Of course, I would only start when I know how much is allowed to remain. And I just want to be prepared when the decision is made. And maybe there will be offers regarding the needed materials in the meantime But since I don’t know whether it can be smoothed out at all, etc., I obviously don’t know what kind of material could be suitable just in case.
Is your house being plastered or faced with bricks? If it is being plastered, take the plasterer, ask him how much he wants to make the thing "nice". If you're lucky, you'll get off cheap.