German markings: Most swastikas were a small one on the vertical fin.
Leave it off if you want. German crosses, IMHO, are OK.

Japanese markings: as far as I'm concerned, copy them 100%. I seriously
doubt there are going be many people concerned about it, other than the
PC types who think the Japanese were "victims" because of the the nukes.
For them, I give a eye roll.

Some things, like the swastikas, can offend a race of people, even if
its historically correct, becasue of its connections.

OTOH, I know of no markings from the Japanese that would be offensive.
The rising sun, maybe, but I doubt it.

In summary, if someone wants to be touch-feely about historical aircraft
markings, I say, who cares! You cannot change the past, and replica
aircraft and paint schemes do not necessarily reflect the attitudes of
the governments or political parties of those countries.

Remember, someone has to play the south in civil war re-enactments.
Thats history, not hate.

John