I'm having a hard time knowing how dangerous it is to drink once from one of those glasses. How many times till I reach dangerous dose?
According to the WHO[0] the tolerable daily intake (TDI) for uranium is 0.6 µg/kg body weight per day. So, 42 µg/day for a 70kg/150lbs person.
Worst case scenario for drinking 5l of water daily from those glasses would give oral exposure to 3.15 µg in total. Even if you were for some reason a vinegar enthusiast 1l/day would leave you with "only" 30µg.
Maybe you want to err on the side of caution and don't try pickling with those.