The Tamron breaking down so early in its life does not bode well for being able to count on it when needed. using three dabs of glue to hold a large diameter element in place is really cutting corners. I'd expect them to be failing in droves before they are a year old, and as the adhesive dries out a little more.
I would hope they make a production adjustment to address this.
I believe they will. However, how soon? 6 months or 1 year? The good thing is Tamron give 6 year warranty. For normal users, they shouldn't worry about the glue issue. If the glue is not strong enough, the glass should fall down in 6 year. Tamron will repair that and you also can ask Tamron do adjustment for your lens at the same time.
However, for PROs you cannot afford two weeks without a 24-70mm lens because that's your tools to make money.
I believe Tamron is good enough for non-PRO, and a PRO should get Canon 24-70mm MK2. My 2 cents.