I would have liked to see pics of "peeling" eternabond tape.
You did it right with Lap sealant.
Lap sealant will never cure into a hard substance, it will always be gummy. It is also easy to scrape back off with a putty knife or similar tool. That is what it is meant to do. Be a short-term sealant that is easy to redo every few years. Never use silicone, while it seals great and last a long time it is very difficult to impossible to scrape back off, so re-doing "caulking" is difficult. Silicone is a mess and a disaster.
The Eternabond tape is good stuff, but not great at small crevices where it needs to get into small corners or cracks. The tape can be used in conjunction with Lap sealant also.
Sounds like the self-leveling was the right pick too.
If there is an option to replace the rubber seals and that is where the leak is then replace the rubber seals for sure...
