You seem to not be understanding so let me break it down.
Playable - you can play as this
You have a list of playable character options in the character creation section of the phb, and additional ones provided by sourcebooks.
If it isn’t a playable character option, it isn’t playable. RAW. It isn’t an option. It isn’t playable.
RAW. Let me get that through your head.
“Rules as written”
Not RAI.
Not “rules as intended”
RAW.
Written.
I’d have to see the mapeditor and confirm it’s any good to care. We’ve had pretty capable (gen 3) map editing tools for years already. Considering what existing romhacking tools are already out there, I’m pretty skeptical that this will provide anything of value.