Sea 4 / Sea 5 - If one of these seas is known for having a peaceful climate, they can be called "The Still Waters". Sea 5 would be most likely to have such a climate to be called that. The other sea can be called the "Sea of Ursprung", and can have a history around it that the gods of Eizon birthed the land and its people from rare minerals found deep within its waters. Or something like that. Connecting it to Sacerestus Peak would be pretty solid.

Ocean 3 - The Adnexus Ocean. (Latin for "connecting" ocean - haha, connects the sides of the world!)

If my neighboring country men concur, then let those be the names for those waters.

Just a question I realized - I'll post it in the Misc thread. Do we know the shape of the world? If so, is this a Mercator-projected map? If so, then it should be noted that areas near the poles in Mercator-projections are distorted to be far larger than they actually are. (Ever see those maps where Greenland is three times as big as Australia? Yeah, that's what happens.)