You might want to update LC and SWP. The LC Onslaught should outnumber the Cathedral 15-to-2 if Alex programmed the game's ship spawning system correctly.
Okay, so I updated SWP and, sure enough, with Luddhancement active Cathedrals now spawn at what I would say are relatively acceptable levels. Not low enough for vanilla-adjacent status, mind you, but satisfactory from a gameplay standpoint at least. It seems a bit odd that your patch notes for version 1.10.5 don't mention Cathedral spawn rates being changed at all, which is why I missed it since the updates that
are listed in the patch notes didn't seem like they'd significantly change anything about the write-up SWP was going to get in the mod guide.
Here's the thing, though...
I also tested the game
without Luddhancement active, and in those circumstances Cathedrals simply do not spawn. At all. Ever. I did a ton of ForceMarketUpdates at the size 6 LC military market from Stop Gap, looked at raiding fleets, looked at invasions fleets... and there was not a Cathedral to be had anywhere... just Legions. And actually? I don't know if this was intentional on your part, but even if it
wasn't this seems like a prime example of Good Bad Bugs, or, "It's not a bug. It's a feature!" With Luddhancement being required to bring Cathedrals into the game, that makes it quite easy to place SWP on both modlists, much like how VSP and Kadur only become non-adjacent when Vayra's Sector is active. So I, at least, would strongly encourage you to keep this as it is. But what do you intend to do?
EDIT: I had it suggested to me that Stop Gap might be responsible for messing up ship spawns, but I tried it again without it and the exact same thing happened - no Cathedrals unless Luddhancement was also active.
EDIT 2: So it gets weirder. It turns out if you have Vayra's Sector installed at the same time as SWP and Luddhancement, the former effectively "turns off" LE's ships, reducing the Church back to just generic Legions with no Cathedrals, as if you were running SWP without Luddhancement.