Allow the usage of Generative Polly for a more natural sounding voice

Polly has a new Engine called Generative. Trying to figure out what to change in order to get the the new voice.
Currently loading the demo-babylon project and working off that.

Tried the easy way of just adding "generative" to the list of allowed engines. Didnt work. Surely something is missing. Help with a solution or point me in the direction to take is much appreciated.