I thought it was just fan made as well but somebody left this comment on blabbermouth and it made more sense
"I don't think the original cover was fake. it was leaked by the artist and it ticked Jari off. Jari told him to remove it from his myspace, which he did, but by then the artwork had spread everywhere. With the advent of splitting the album in two, plus the amount of time that had passed since the leak, Jari probably felt it was best to commission a new cover. The original artist was paid and that's that. Had he not jumped the gun and spoiled the Time cover, his artwork might be the cover of Time I (with a re-painted title).
Also, the major themes of the covers are too similar to be coincidence: a japanese tree (no clue what it is, but to me it's just a blossoming cherry) and space and stars. The passage of time.
Honestly, I feel that the leaked cover is very mid-2000s and would have worked back then; the 3D band logo, and great follow-up artwork to "Wintersun". But a lot has changed in the past eight years. The newer cover, which is growing on me with every viewing, is what the *third* Wintersun album might have looked like, had there been a second album back in 2008, say.
In other words, this artwork seems to follow a natural progression, but we simply skipped over eight years, and instead of a third album, we're only on the second. I hope that makes sense"