All things aside, no one has asked if you had the recall rear O-ring replaced along with the fuel pump O-ring and headlight harness that Yamaha put out for the first generation Tenere's?
Your 2012 fits the bill.
This is what i did when my rear started leaking most likely didn't let it completely weep out of the hole before i screwed it shut.
Take the bike for a good half hour ride put it on the center stand and pull the fill hole plug while it's hot. The expanded fluid will flow until it stops.
Plug the hole and after it cools over night check it with a thin strip of bent cardboard as a dip stick, it may be just a tad below the hole.
Haven't had a drop on the floor or around my rim in over 10k.