Don't be disappointed man, your complaints were fixed.. :)
After more checks to the mod this is what i see:
1- The mod uses humidity/heat to spawn biomes to have it's special way of spawning biomes and make the biome spawning more realistic, it does not need to use the same ways that other biomes use..
2- The mod actually did not spawn only savannah but you are right, it was not very random and savannah was very common to be spawn after the last update, it will start the spawn of the world more randomly :)
3- wild onions will grow slower, however i do not see why all crops need to have the same growing speed..