She won't speak. Not a single word, y'see... And she's using a fake name too!

Admittedly, she's pretty fluent in body language (read: violence) though.

Could you do your fortune-telling dealie and find out how to make her talk?

Leave it to me!

They can't just develop her character willy-nilly, which is why she can't speak.

Because Cygames hasn't gotten any acknowledgment on using that umamusume. Cygames ga kyoka toretenai umamusume dakara, i.e. "Because she's an umamusume that Cygames hasn't obtained permission for yet."