We do all know, but the tooling for IL2CPP is not mature yet.
This is on illusion, they jumped into it due to laziness, they ought to make their games better instead of trying to cheat with changing from Mono to IL2CPP. Seems to have paid off for performance, but equivalent exchange, it seems to have doomed the game to a failure. Time will show though.
Make no mistake: They didn't move to IL2CPP due to some 'new functionality' spell or anything, it's a way to attempt to avoid needing to make proper improvements.
Seems Japanese users are tripping around waiting for UncensorSelector, ABMX, Wideslider, Overlay... so this will hurt their home market as well, not just the western market.