My understanding of the squat switches is they work in conjunction with the static system to prevent ground retraction and that they also operate the Red/Green lights to show gear state.
I have never seen a Duchess fitted with un-feathering accumulators! I know it is possible, just personally not flown one with them.
I can email you a copy of the POH and the Multi Engine training notes on the one I use most frequently if it helps you.