Once any plant has been inside for a while (a month a more,) the leaves are probably no longer used to that much sun.
Gradually introducing back to outside can help prevent sunburning the existing leaves, and is the conventional advice, but in the case of something that grows new leaves as quickly as Coleus, burning the leaves could be quicker than trying to acclimate the existing ones. That's what I usually do.
If they have retained the same color, leaf angle, and node spacing, they could be OK. Sounds like you have several of each. You could do half each way in case one doesn't produce good results.
