With the context we now have about Cassandra and Ankarna, and after rewatching the scene where Kristen gets so sickeningly manipulated by Sol and Galicaea, all of their goals become more clear. Everything Galicaea was doing was to keep Cassandra hidden and trapped as the Nightmare King, and Kristen was caught in that crossfire. It was Galicaea's own most loyal tribes who brought about the initial destruction of Cassandra's identity in the early days of Sylvaire, it was her who destroyed all evidence of her sister's existence, and it was her who fought so hard to keep Kristen from communing with Cassandra. This becomes the most clear when Kristen brings up doubt for the first time, and Galicaea snaps back at her, saying "doubt is nothing" - almost like she was the one who turned the Goddess of Doubt into nothing. Oblivati Mori.
I only wonder how this affects the fallout between Tracker and Kristen's respective faiths - Wolfsong's success as opposed to Cassandra's "death" is an exact parallel to how it's always been. Big sis Galicaea getting all the praise while her sister gets screwed over. After all that Kristen's done to keep Cassandra alive, and with what we know about tomorrow's episode, I have a feeling we're going to see some huge events surrounding this pretty soon.
I’m fully convinced the “walk out” moment is Kristen succeeding on a divine intervention roll so well that it connects her back to Casandra. This could even come about from Tracker’s apparent doubt in how Wolfsong is doing. Like you said, when Galicaea is in full power it appears to go in direct competition with Casandra. The wedding between Casandra and Ankara could have been a way to get around this but at some point Casandra was turned on further and became the nightmare king. that could have contributed to Ankarnas fall.