2012 Outback 3.6R transmission issue

As the title states I have been having an issue with my Outback. It has been going on for a few years and has progressed. It is the 5EAT transmission, and I always thought it was a torque converter. Came to that conclusion thru a mechanic (doesn’t specialize in Subarus) and some research.

Finally I decided to take it into for another opinion from a local shop. I am now learning it could be the valve body or the TCM. I can share their diagnostic notes in the comments as well. Throwing codes P1710 and P0700.

The car would rumble or shudder between 40-60MPH (a/t oil light flashing and occasionally the shift indicator on the HUD would blink and disappear) and that was the only symptom until recently. 3 times in the last 2 months I have had the transmission slip. Scared the hell out of me the first time.

Is this it? Is this the end? Being quoted $3k for a valve body and have been strongly advised against a refurbished. There is an option to replace the TCM with a used one for $500 to see if that clears everything up.

TLDR - P1710 and P0700 codes on a 5EAT - Valve body, TCM, or something else?

156k miles - issue has been going on since I bought at 114k, and likely before that.