OK, I think I have my rear brake bleeding issue figured out. In my situation, I wasn’t getting brake fluid through the ABS module. It was reaching the incoming ports (H and V) on the base of the ABS module, but was not exiting the rear brake port (h upper connection). I was getting fluid to come out both the front brake module ports though (l and r upper connections).
After trying several things, including attaching a spare bleeder valve directly to the outgoing module port, I came up with a theory. Casso’s comment about the fluid still being able to travel through the module even in the event of an ABS failure makes complete sense, especially from a safety perspective. Additionally, if the brake fluid enters the bottom of the module, travels upward through the module valve, and exits the top of the unit, possibly it needs to be gravity bled to a degree. My thinking was that if the lines were dry from the module to both rear calipers as they were for me, possibly the fluid could not pass upward through the module valve.
What I ended up doing was disconnecting the h port on the top of the module. Then I took a short piece of hose and slid one end over the flared end of the metal brake line and placed the other end directly into a bottle of brake fluid that I had wedged between the module and inner fender. I then went to the back of the vehicle and began bleeding the rear brakes like normal. Doing so pulled the fluid directly from the bottle and essentially filled the brake lines. Then I removed the hose and bottle of brake fluid, reconnected the metal brake line to the h port, and bled the rear brakes again. I was hoping the first step would leave only a small section of air in the module while the rest of the line would be filled with fluid. Now I was able to bleed the fluid through both rear calipers pulling the fluid through along with the air.
I haven’t driven the vehicle yet, but the pedal feels firm now. Keeping my fingers crossed, but hopefully the issue is now fixed and I’ll be able to drive my car again soon. Also, I’m still working on the electronics of my ABS system and have eliminated many of the possibilities. If I get it figured out as well, I may post a writeup on how I went about doing it in case anyone else deals with the same issue. Thank you all again for the awesome responses and debate about this topic!