I did saw the Post Battle Mourning did have Berkut was meant to be playable in the beta along with Frenand besides the Rise of the Deliverance. But, I managed to found a video that Death Chaos (the same user who posted the Post Battle Mourning Voice Clips Quotes) managed to find more of Berkut's quotes that he very well most likely have been planned as a playable character during in the development. I did not see anyone posted a thread about all of Berkut's unused lines in this forum section and this video was posted around May 25th.
By the way, the user named Death Chaos managed to post the timestamp in the description that showed what timeline that one of those voice audio clips belong for any of Berkut's line in the game data: