I read it through several times because I didn't understand Tarvek's intentions. This strip and what comes after clearly indicates that Tarvek deliberately changed Anevka's head to Lucrezia, and while we have no indication since then that he would be conspiring with her, we also have no indication that he would regret doing this. So until we get a clarification on why he did this, he remains at least in the "suspicious" state for me.

About the new update:
Spoiler
Show
I think Klaus is trying to save what he can. He decided to taka Agatha alive to avoid carpet bombing Mechanicsburg, or at least save some time until Gil can unwasp him.