I have noticed the Spanish / French / Jolly Ghost ships got an HP boost (took several lighting and broadsides to bring a War Sloop down??) and they do shoot the firepower at you (sorta - it didn't damage the WF too much) - but the crews are mixed up - a L29 ghost ship with only L9-11 crew.. but a L19 ship with L17 crew?

LOL
Note - a driect broadside hit (not front or rear) did MUCH more damage (10% vs 60%) on the Ghost Sloops... just an FYI