>>715929959a little of both but i guess rollback takes priority over the balance changes in USF4's case.
as for other titles like alpha 2, alpha 3 and sf3 they could easily have balance changes and more.
in alphas case the could just add all the character from that psp port to both alpha 2 and 3, with the necessary balance changes and stages from previous versions. in sf3 case would be much needed balance changes, bug fixes and add all stages and ost from the previous 2 entries.