This Bug is related to
https://bugs.mojang.com/browse/MC-197616
After creating a World with a CustomBiome you need to relog (to recive the CustomBiome Data)
Or else the Client don't know about this Biome and will spam 'Received invalid biome id: 222' (id may be different) in the Client-Log (this will cause huge Lags and Game-Crashes)
Also the "replace=true" while registering a CustomBiome may now work better.