Currently ChunkProviderOTG does not publish a ReplaceBiomeBlocks event before block replacement like Vanilla does. This makes it difficult for some world-generation mods to hook into OTG. My mod Streams for example, needs a coremod/reflection-based patch to trigger it which is of course very brittle and likely to break if OTG internals change. So for OTG to send the event on its own would help keep Streams and similar mods supported in the future.

( Implementation suggestion: at the beginning of ChunkProviderOTG.addBiomeBlocksAndCheckWater(), call ForgeEventFactory.onReplaceBiomeBlock() in a similar way to vanilla's call in ChunkProviderOverworld.replaceBiomeBlocks(). )

Hey, thanks for reporting this. There may be other Forge events OTG isn't firing, I try to keep track of them but it can be hard to find all of them :o. Will see if I can fix this for the next release. Nice work on Streams btw :).

Sorry for the late repsonse. Need to review ChunkGeneratorOverworld and look for any more significant differences/events that are missing. Will see if I can fix this for the next release (v7).

onReplaceBiomeBlocks should be being called before block replacement during terrain gen now. Will be included with v7_r24. Is there any way to test this with streams?