I think that the surprised status is fine - and in fact is exactly what should happen - when combat starts on your first attack, it’s the fact that combat doesn’t always start, or start for all your party, that’s the problem.
There was a recent discussion of how starting combat from stealth, or just where the enemies can’t see you, could be handled better at
https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=838946#Post838946.
