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And regarding Velvet, Magilou and Rokurou in Tales of Zestiria the X: they just appear in episode six and seven which adapt (in a modified form) their escape from the island of Titania.
They aired Aug 7-14 2016 and Berseria came out Aug 18 so I guess Bandai Namco simply wanted to promote the game through the Zestiria anime...not a bad move at all considered that Berseria was a very successful title.