Very good work on this! Nice to see.
It seems the batteries must have been really low so the WFCO saw its trigger to go into Boost, because the wiring shows a big voltage drop with the 60 amp flow. That indicates the wiring is still too long and thin, so the reduced R is all from the battery bank being low (I think-)
In my experience you need say 3 ft (one way) of no thinner than #4 wire to get 60 amps with a 55 amper. That's with a converter that does not have any 13.2 thing.
The battery end of the wiring has lower voltage than ideal because of that voltage drop, so the battery is not getting the full benefit of the higher voltage from the WFCO, adding to the time in absorption (I think-)
I expect you will be able to keep the WFCO acting right on batteries not quite so low if you fatten/shorten that wiring.
