Ah! Sadly if the solution was that easy, it would have already been fixed...
You would have to crop larger tiles, apply PCV, and then crop them again... Not super easy.
Anyway, due to the way PCV works, you'll always have some differences of brightness / tone I guess...
PCV AmbientOclusion in multiple clouds of same scan
Re: PCV AmbientOclusion in multiple clouds of same scan
Daniel, CloudCompare admin