here is a site that does a good job of illustrating the inner workings of an abs pump:
https://www.brakeandfrontend.com/abs-esc-hydraulic-control-unit-modulator-diagnostics/
you can see that an improperly seated/leaking valve would give the fluid a place to go that isn't the caliper and cause the pedal to travel further before it engaged.
i guess first step would be to determine if your issue is engagement point (i have to push pedal further) or effort (pedal is too easy/hard to push).
a quick search for symptoms of failing abs pump indicated that progressively non-responsive brake pedal is one of them.
and hey, it's the one component you haven't replaced yet (because it's expensive). if you do change it, note that there are multiple versions based on year and types of traction control, so double check part #'s.
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