I can't believe the level of discussion around the propriety of ship names.
It does not matter what a unit is called. Other than the education of the player.
If you honestly believe people who know what 'arquebus' are, can't figure out what 'pentecoster' are. Then you are deluding yourselves.
Thal, if you want to change them, change them.
But, if the way a unit is
used is going to change, that needs to be discussed.
If I start a game and, without being aware of changes, select say a "Galley", in the hopes of pounding coastal settlements and barb camps only to find on use it has now morphed into a MELEE only ship-killer. I will be p****d. (Actual ship name in example is just for argument. Not meant to relate my preferred role.)
On the other hand if I look for my "Galley" and find it is now called something else. I'll go "Oh really, I did not know that, that's interesting." And then quickly get back to playing. If the role of ship fits my purpose at the moment then that is fine.
I did it with 'arquebus'. I did it with 'dragoon'. I could do it again with any other unit.
For all it matters the line of ships could be called: "Sleepy, Dopey, Happy, ... Doc".
[Sorry. Didn't sleep well. A bit edgy this morning.]