Riley,
My attempts to source cruiser blueprints have been unsuccessful. An offer has been floated to sell us additional Hel-class cruisers, but that still runs into the same logistics issues that Black Cloud II has.
We know the Houses won't part with their blueprints, Crayter didn't share Hydra plans so I rather doubt they'll share Thanatos blueprints, and we can comfortably write off the Storta and Fearless.
There are, of course, other options.
How hard would it be to convince Bretonia to allow us purchase of some of the wrecks from the invasion? I don't much care if we get Crecy, Storta, Triumph, or Penance wrecks, but if we can get enough samples to work with, Aquila should be able to reverse-engineer enough to accelerate their own design work.
While a corvette would be an easier project, I'm less concerned with our corvettes as several effective models are available on the open market already, and sourcing Montante, Condor, or even Ahoudori blueprints should be little trouble. And we need something heavier than a corvette as a successor to Metropolis