Afaik, Moeha Fujiwara and Kaguya Shinomiya have interacted on-screen only in S02E02 and S03E10. Their conversations are broken down into:
S02E02 at the start of their outing with Chika and Kei Shirogane when Moeha talks about Kei to Kaguya (Moeha: Kei is cute, and I want to lock up Kei in a dungeon.) - Not keigo. - See 0:11 to 0:25 here.
S02E02 briefly right after (1) above when Moeha talks (about Kaguya) to Kaguya. (Moeha: You're at the top of my list of things I love to the point that I'd want to eat you.) - Keigo. - See 0:32 to 0:40 here. (I guess 0:25-0:32 isn't keigo, but I guess I won't count it for the same reason as (3) below.)
S02E02 at the end of their outing when Moeha invites Kaguya for a group hug - Either not keigo or N/A since just 1 line. - See 1:25 to 1:30 here.
S03E10 when Moeha talks about Miyuki to Kaguya - Keigo. - See 2:20 to 3:01 here.
Summary: The only time Moeha doesn't talk keigo to Kaguya is when Moeha is talking about Kei.
Question: Did I get this right? If so, then any particular reason that Moeha doesn't talk to Kaguya in keigo when it comes to Kei? If not, which part is wrong?