Sorry, didn't see it before.

Well, the idea is really nice and fit well with the rest of your serie.
The only revelant comment would be to up the CR because while the ability damage is temporary it's still very brutal at low level. What's more it's a flying creature so at this level only range attack can attack it.
It could be even worse if the original creature had a burrow speed, in that case nothing can target it.

Apart from that detail it's very well made, good work.