Lanterk was furious and was tempted to destroy Lara and kill the Presider that dared disrespect her. But Zeraphine's words held a lot of mystery.
He was able to deduce that Crostfree was alive, and this alone kept his anger at bay.
Crostfree was a Top-Tier Presider who managed to fight Garenjazz to an equal. Garenjazz was the only Presider on this solar system that Lanterk feared. In Aragar, he already had encounters and crusades against Garenjazz and lost spectacularly.
How Corstfree became one of Garenjazz's equal rivals confused Lanterk to no end.
What also stopped him was the sudden announcement. The Progenitor didn't even hide and even spoke out loud. The masking techs that made it difficult to confirm which of the Presider was talking made Lanterk wonder.
Zeraphine, on the other hand, was very angry. But Lanterk's understanding of why Zeraphine was angry was way off the mark.