There's always the various starship books to go through.... I'm sure that Models Please hasn't managed to model everything that appears in the Jackill's series quite yet.
I tend to draw inspiration for vessel type and roles from current and WW2 navies. All the races in SFB / SFC should and would have a comprehensive fleet involving not just capital and perimter ships but miselaneous auxilary and support vessels, stations and facilities.
Then there is the merchant fleets that all races operate for their economic infrastructure and inter race trading.
If anything, freighters are the most important vessels in a naval war.... no freighters = no supplies, no war materials, no reinforcements and no successful war economy.
It does seem odd that in SFB that war build freighters would be more "tweaked for speed" that pre-war designs. It is also kind of obvious that predation of freighters in wartime by hunter killer and other specialist warships would motivate the various races to build faster freighters along the same theme as the WW2 liberty ships.
Its something to consider.