Quoting Rhonin_the_wizard,
Before doing that, go to \Documents\My Games and rename the GC3Crusade folder so something else, like GC3CrusadeOld.
I'm back with a status update.
So I did as you said and renamed the old GC3Crusade folder before uninstalling and reinstalling, so that it created a new GC3Crusade folder. After reinstalling, I ported over my ship designs from the old to the new folder, and tested it out.
Initially it seemed to work, as my Carrier Modules spawned Missile-using Assault Fighters. But that changed after I started a new game and used the console to refine my ship designs.
Once again, it spawned Beam-using Interceptors;

Right, that's annoying. Because this game had all three weapon lines fully researched, I thought it was possible the game chose Beams at random.
So I started another one, and this time limited my console usage to quick research only the Missile line in the tech tree on the off-chance that doing so will make the game choose it as the weapon equipped on spawned carrier fighters.
Nope. It produced Beam-using Guardians instead;

It's like my copy of my game has some strange obsession with Beam weapons for some reason.
So. Think you could take a closer look at this issue?
Hi,
Now I understand your Problem. The Loadout of your ships per se is ok, but they are spawning interceptor. For this topic I think we should understand how interceptors are made.
Personally I think that this is a Problem with the Hull Type. Tiny ships are fast and agile and therefore interceptor. Try my mod/suggestion and change the Hull from "Tiny" to "SMALL". I think then you will get your assault Fighters.
Then copy the script from the "Fury" Fighter (without life support and engines) into the CarrierAssaultfighter typ and you will always get a small Assault fighter with the best weapon Tech.
Yeah, based on my latest experiments detailed above, I'm starting to think the Hull size is what's affecting what my carrier fighters are spawning with in such a weird manner.
I might try this suggestion of yours later, and see how it works.