MLHFM and KFKHFM also have to be changed
Yep. Even with the same housing, MLHFM is different between bosch and hitachi. See S4 551A vs 551M (for example).
Historically, people have gotten away with not copying over MLHFM, but it is "wrong" enough that it is advisable to copy it.
KFKHFM is debatable, though. That seems to be more dependent on airbox configuration than MAF
YMMV.