I find the apparent necessity to have everything defined by exact numbers and to make perfect sense tiresome these days.
Gallia was constructed to serve a role, an antagonistic one. To properly serve it's role, it required power above and beyond what already existed in Sirius and was granted it via it's lore. Assigning any number to fleet compositions is an arbitrary and ultimately pointless exercise, all that needs to be known is that Gallia is a small measure stronger than Liberty, and several degrees stronger than the other three houses.
It's a storytelling exercise. JRR Tolkien did not bother explaining where Sauron got his hordes from beyond the basics. The evildoers in Wheel of Time have apparent access to countless armies. The White Walkers in ASOIAF have undefined strength but are definitely an existential threat. I could go on.
