I love what you've put in. Every bit of it.
What are the chances of getting racial feat's for these races? I loved the idea of it for baseline 5E, and would love to see that in here as well. I feel like there might not be all that many people that feel the same as I do about this, but it would be nice. I'm a fan of Changeling's, so Maybe a racial feat that gives it darkvision and something else for its Change Appearance feature, or upgrades it's one or more of it's other features, and have the flavor be something along the lines of your more attuned to your doppelganger half than most.
Just a thought.
Keep up the good work, Peeps. Love what you put together.
[5 of 5 Stars!]