The fix posted is only for the intake side so that it can take in cooler air. But the exhaust would remain to the seat back cavity, so eventually the seat back will heat up to a point where it can no longer be cooled by the TED. The best fix is to have both, intake & exhaust routed outside the seat back.
However, your Edge is a 2017 model. Midway in 2016 Ford added a "sock" for the intake so it can take in air from under the seat. So your Edge is good on the intake side. To improve your seat back cooling you need the exhaust side. Unfortunately, the guy (Tim) who used to sell those kits doesn't seem to sell them anymore. But I remember some F150 owners making their own fixes using duct tape and tubing. But I couldn't find any searching now.
Also, the F150 thread you linked talks about another issue some are facing with their seats, it is an electrical issue, if it happens causes the whole cooling/heating function to stop.