Where are you getting that from? FKG doesn't declare its artists in-game, and Gerbera's artist never came out, so we have no idea whether there was a change in artists or if the guy just improved naturally in the two years he had between the initial and blooming commissions. I mean, just look at Kancolle's Bob.
FKG never changed artists for a character in any other case, so there's no reason to think they did that here, especially since awakening and blooming art are in fact very similar.