HUMMMM! sounds like a universal problem with the Wilwood product....plastic crap.
Mine plastic craps have been on the car for over a year now and no leaks so far, if they start leaking I'm going to the CNC type, besides they're shinny.
Actually, the plastic reservoirs are very good with respect to placement and visual inspection (at-a-glance fluid level)..I like that feature.
Perhaps too much heat, and overtightening causes the things to distort and start leaking, but what do I know?
I do however agree with Madmax, Seal-All is the greatest stuff..it fixes everything and is clean (clear). Gas tanks,
oil leaks on small fittings..so why not brake fluid on crap plastic resevoirs.
Bill