After some digging, the crossover point for the bass enclosure is 83 Hz, and for the RTR6 high pass filter, via its own filter network is 7500 Hz. The amp goes in to the tower at the lower woofer screw plate, with a daisy chain then going to the RTR electrostats.
A single RCA bridges to the upper screw plate, which is then fed to the FMI80. I assume there is a simple resistor set to reduce the low freq. content to the two series connected tweeters, which would be allowed to naturally roll off.
For further confusion here is the woofer crossover, sure to induce nightmares.

Now you can see why I am so surprised they not only sounded good, but close to great at their wheelhouse of recordings. If I moved them towards the wall, I could improve the bass, but at the degradation of a little clarity with the electrostats. Where I had them for the gathering seemed to be the best tipping point for retaining enough bass without creating a strong delayed high end.
I'm wondering if it would be worth pursuing a pair of J Modular woofsie cabinets, which supposedly has markedly better bass at all positions. Any opinions?