I'm not familiar with all of the original names/codenames for things, but here are those that I know:
Coronata: Eidolo (IIRC)
Eradica: Cherubim (IIRC)
As for other ships.. Well, the Advent are pretty straight-forward with most of theirs. As for the TEC..
Arcova: no idea
Cobalt: no idea
Javelis: javelins were once a prominent long-range weapon
Krosov: no idea
Percheron: no idea
Hoshiko: no idea
Cielo: Spanish for "cloud." Presumably because it is a command cruiser and is somewhat "above" the action
Kodiak: It's a bear. Strong and don't like to die. Appropriate for an HC.
Orgov: no idea
Envoy: I can't even remember the name, let alone tell you why it is called that.
As for the capitals, no one knows for any of them but most assume that there must be some esteemed Admiral Kol or something.