I prefer the Commie fansub group's transliteration of the title given to girls like Mamori, "Ecsta", over Funimation's, "Exter", because it shares a root with "Ecstasy". ("Exter" could be either "exterminate" or "external", neither of which fit the context as well.)
Also, in the comments to their release announcement for Ep. 3, Commie seems to have decided to go with “Wärter” or “Waerter”as the name for Gov. Akira's little band. It's German for keeper/guard/warder. Everyone else is saying "Welter", which makes almost no sense in this context; it means "to move in a turbulent fashion".
Don't know what the original script says, but since these are both words with foreign roots (foreign to the Japanese), I wouldn't be at surprised if they themselves got them wrong.
Anyway, barring contrary notions from other editors, I'll be using Waerter and Ecsta.
It strikes me that "Ecsta" and "Liberator" are very clever bits of propaganda. "Liberator", especially, since it seems at least some of those are rather abusive of the Ecstas.