It's transformative insomuch as this is a new arrangement, new sounds, new melodies. Sure, Jochen made the original, but remixes are in general covered under fair use. In cases where they are not (such as this might be, as it's still a close adaptation of the original in arrangement) you generally require the permission from the original author to spread it.
I can't say I'm a legal expert, but remixes in general are probably more derivative work (requires permission) rather than fully transformative now that I think about it. In any case these particular tunes can no longer be bought, the original licenseholders no longer exist and the original artists themselves encourage people to make remixes, so as far as retro VGM music goes it's pretty much green light no matter what you do.
