And you know wile I was look at the link you put in your post I look at it and I found something VERY interested. And it may just the thing New Republic needs for it's own BattleCruiser The Bulwark MK3.
Theoretically there are a lot more ships that could be added to the mod.
But if you would add all the ships in the Legends canon it would be waaaaay to much.
Plus some of the Ships wouldn't have a good counterpart.
It's all a rather fine line between balancing, work that need to be done to put them into the game and use of the ship.
Plus many ships fill the same role, so why would you want to have 3 ships that do the exact same thing, cost the same amount and are just named different.
As it is this mod has added a lot and in 2.2. a few more ships will be added so there is that