When the shoes were left behind, Dale was returned to the world incomplete. If he gets Mr Cs shoes, he will be restored.
I follow your logic, but it might not necessarily be that simple. We cannot assume for sure that the absence of the shoes is the reason for Dale did not emerge properly the other side. Also, if you take that logic to its extreme, it would mean that every time Dale was not wearing his shoes in season 1 and 2 we would have seen him acting stupid.
But if those shoes aren't important, why were they left behind? The part where Jade helps Dougie put on his shoes seems to emphasize the fact that they're missing. Whatever the case, I'd rather see Coop come back via Laura or another means instead of just getting his shoes back.