This is probably a limitation of multiplayer
It is, but there should be a middle ground. While it's fine that the other player remains in real time when he's far away enough, it's honestly exploitable as hell that the same player can stay in real time even in the middle of the battle area as long as he's in stealth.
When a players/characters are close enough to the action they should join the turn-based timing of the battle, period.
