Well it's more so, that Beryl is like one of few individuals I could see being able to summon the likes of Morgan Le Fay, with crypter servants having to be from PanHistory, and have a connection with the land the lostbelt belongs to, plus a strong enough reason to want to support this type of lostbelt, which is funny cause she is essentially usurping the lostbelt from herself, but I could also see that being something she would do given her contradictory existence, of hating Artoria, but also realizing she is the Rightful King of Britain later in life. (Perhaps even Mordred being a sort of extension of this thinking.)