That is for you to decide, I'm not going to tell you how to fit your fleet.
As for the assumption that the Domain never used Mora or fighters at all is just wrong. Read it however you like. The Mora carrier was alongside the Onslaught before the collapse of the Domain which preceded nearly all mid line and high tech ships.
As I understand it the XIV Legion was part of the Domain navy and it replaced the Mora. You need to provide proof not conjecture to the contrary.
It is even stated the Mora was decommissioned before the collapse while the Domain was still spreading and colonizing worlds.
"After the Collapse, Mora hulls were re-militarized almost suspiciously rapidly by factions that did not possess dedicated fleet carriers. Today they are an anvil upon which many an unwary Pirate warlord is broken."
Your whole argument hinges on this statement here.
"A venerable design the Onslaught-class battleships were first created to serve the Domain of Man eons ago, before the development of advanced strike weapons, fighter craft, modern energy weapons, and shield systems."
You've taken it to understand there were no fighters, but the statement as a whole means "advanced fighters".
There were carriers and fighters before mid line and high tech. They just weren't advanced.
Here again you took a statement out of context.
"The Conquest-class battlecruiser is the embodiment of concentrated firepower. Developed in the period just preceding the popularization of fighter craft, the class emphasizes firepower and speed over armor protection."
Fighter craft clearly existed before but were not yet popular.
You seem to be unwilling to digest all of the information available. I'm beginning to suspect you are a gamma level AI