Instead of having to choose one, every unlocked perk is automatically enabled now. Assuming you are using the dragonguard class and you have unlocked the third perk (there should be a green checkmark shown next to it), your hero should count as a dragon.
I just checked with my “counts as wildfolk” hero (bard class) and that is working correctly. I get the “4 wildfolk” team bonus and my King Silenus gets 24 damage boost per cast (6 per troop).
If it really doesn’t work for you, describe how (team bonus? not getting extra damage for a troop?) and I’m sure they’ll look into it when they find the time 
(screenshots are always nice too)