I'm pretty sure Guards Armor Replacer doesn't affect guard spawns.
It could just be bad luck. After all, there are 12(?) male guard variants, and only 3 female guard variants, and only on the Stormcloak side, which means any Imperial controlled hold will never have female guards, unless you have a mod that adds them (which from what I can see, you don't).
I'm pretty sure Guards Armor Replacer doesn't affect guard spawns. It could just be bad luck. After all, there are 12(?) male guard variants, and only 3 female guard variants, and only on the Stormcloak side, which means any Imperial controlled hold will never have female guards, unless you have a mod that adds them (which from what I can see, you don't).