The costume bonus is certainly a placeholder / copy-pasted from classic (first) costume bonus for now. CF1 costume bonus got buffed THREE times up to this now:
It would make no business sense to release CF2 costumes with those stats in today’s E&P so it will certainly be buffed before release.
Regarding CF2 costumes in general, I was hoping for Slayers costumes first as it’s the family I have the most heroes from so was hoping to get my chance to pull them soon. I have been saving my Challenge Coins since the last CF1 event so I guess I can wait and save a bit more until Slayers costumes come out 