Coming in a bit late on this but is there big version differences between US & JP that caused there to be a separate board for JP instead of just a region selection on the existing any% board ?

From what I tested, this shows the differences for the version.

The japanese version features a shorter jump height which leads to different strats, as well as different amount of lag. Personally if I was more active as a runner I'd be more opposed to separate categories since it seems like a textbook case of where a region column makes sense, but multiple people in the community who are more active than I am would prefer to have it this way.

This is a long way to say it's that way because that's what the community as of late prefers.

Ahh I see. Yeah when I did my current runs of the game I don't think there was any JP runs at the time and when I did a quick look at them now they looked the same so wasn't sure.