Yes, get your point. You might try the SDK (https://docs.mendix.com/apidocs-mxsdk/mxsdk/) as last resort. I have not tried it myself but it might be doable. Hope somebody with more SDK experience chimes in here for a reply.
Regards,
Ronald
[EDIT]
And as afterthought you might want to try to import your JSON. Mendix will create the non persistent object. I think it might create the enumerations also allthough I am not sure about that one.