Ok, as far as I can, I have edited heroes who have ships, to have the era ships that I want.
Thrawn - Imperator-class Star Destroyer (Chimera) - Dragon Destroyer
Piett - Imperator-class Star Destroyer (Admonitor) - Dragon Destroyer
IG-88 - IG-2000 - Sith Destroyer
Tyber Zann - Krayt Destroyer (Merciless) - Harrower-class Dreadnought
Changes have been made to the following -
Kedalbe-class Battlecruiser - was Strident-class Star Destroyer - Is now Galaxy-class Fleet Carrier
Krayt-class Destroyer - Centurion-class Battlecruiser
New Hero Unit - Chiren Guinn (Guinn Dynasty leader) Personal ship - Executor-class Super Star Destroyer (Because I do not have the Nemesis-class Super Star Destroyer)