@watabou - any chance to get access to the JSON before the desktop version? Here's a look at what I'm doing with it (zoom in on the city in the center, Phonas) - http://notveryprofessional.com/dragoneye/atlas/Phonas -- JSON would be perfect, at this low scale straight-out turning it into GeoJSON is ok because we're talking about a few mm of difference.
I'm happy with the most rough interface. I wrote a GeoJSON export for Azgaar's tool myself (he accepted the PR, so it's now in his codebase). If I understood this Haxe thing, I'd do the same here, but sadly I don't.