There’s simply no reason why a player would in ANY situation use the galleass. It’s MORE expensive than the carrack, does less DPS, and has 1 less range AND with no bonuses v structures. (Funny that its description still reads “+anti structure specialist”).
Yeah, it can be made during Age III, but consider how expensive they are you hardly want to invest in them since they are just useless in Age IV. In any case, you can’t build lots of them in Age III anyway.
I think it would be a good idea to increase its range (for example to 10, one more tile than the carrack, matching the description that it carries a large bombard.) and give it some anti-structure bonus. Otherwise it’s useless and in any case should not be more expensive than the carrack. Or it should be significantly cheaper than the carrack.