I've encountered several common biomes such as 'Highlands', 'grasslands' and 'coniferous forest' from Biomes O Plenty where normal trees spawn instead of dynamic trees, and the trees in these biomes are particularly large and annoying to cut down. I know this isn't an 'error' per se but I'm not sure where else to post this.

This is very strange, all biomes should have generation. I will take a look but if you are able please let us know exactly which biomes are missing generation