Many times it was attempted to establish a "measure" for naval power of the houses, but concrete numbers are impossible, since player presence, rapid sequence of events, and other measures make such specific numbers immediately exaggerated or obsolete.
Once you define a real number, a series of other issue arise. What happens when x number of ships are destroyed? How fast is force renovation? Should they be built that fast? That slow? If they're that fast, why hasnt X house reached xxx number of BS already? If they can do this with this many ships, why haven't they done that thing ? Etc. Etc.
Best thing you can get is "relative" force numbers, like the old "Liberty has a fleet as big as the next two houses combined (excluding Gallia)" things.
Kusari number doesn't make sense, if we take into account Kusari had been living in relative peace after Tau Wars (until KCW of course) and had time to rebuild their fleet - unlike Bretonia, which had been pounded again and again. It's pretty likely Kusari should have more Battleships by now.
I always wondered why, for storyline purposes, Bretonia doesn't just field a fleet of Rocs to take on Gallia. I mean, wayyyy back when the Xeno Alliance was in it's prime, we took on scores of just about any capital ship you could think of with mere Rocs, Eagles, and on some occasions, one or both of our SRP gunboats. Even fighters fell to us simply because we had a good complement of both fighters and bombers. If Bretonia pulled the same trick, would they not see more success on the war front?
Until we start getting complaints, requests, demands and general screaming should those numbers not align to peoples pre-established ideas.
In short; it doesn't effect gameplay, it reduces the amount of screaming we get and doesn't allow for "whose is bigger" contests into which things like these always devolve.