Reported by @rorax here.

More data from @rorax here.

PM with @SirSengir to try and understand what the correct resolution is.

@SirSengir is not using forge hooks. This mod must register it's leaves via forestry API.

The leaf registry was utilized somewhere a while back. It looks like this may ne fixed...submitted to @rorax for testing.

Based on @rorax' testing results are improved. Remaining anomalies are because Forestry'd generation code is tuned to vanilla biomes (for instance hives rarely generate in Redwood Forests because their height is much greater than vanilla forests) Any more improvements will come from @SirSengir in Forestry mod