You got a very interesting and detailed write up on watch radiation. I am not a radiation expert or with IAEA but work in radio-pharma industry. The GM counter can detect the basic three + one type of radiations (alpha, beta and gamma + x-ray thought not very precise, I attached my workplace pancake pic). There are way to convert GM counter uSv/hr reading to Bq if you know the calibration source radiation material and the efficiency of your GM counter for the particular radiaoactive material. Although science textbook tells us that aplha particcles can be block by thin piece of paper and beta can be block by few cm of polycarbon, that is only small amount they are talking about. If you have more than MBq, it will be pickup the GM counter. We should also take into account of bremsstrahlung when measuring alpha and beta particles over/across dense materal like watch metal case. Even if GM counter is not show any reading, it could just be that the dial radiation is in the background range (<0.5uSv/hr). I tested my tritium loaded BALL watches using the pancake and all show background reading. Although given that small sample size testing that you got, but getting 5uSv/hr reading above the dial of the vintage radium tinted dial rolexes, you do not need to get more than 25 samples sizes just to statsitically prove that the vintage dial is still radioactive (as watch dial are not suppose to have any radioactive reading to being with, ie from 0uSv/hr to even 2.5uSv/hr, how many time or multiple is that, infinity?). If you really want to test radiation level, you should do a swipe test and measure using scintillating counter or dump the watch in an ion chamber and measure the radium radiation. I suggest that you should properly dispose or seal away those rolexes if its of valuable to you. Your health is your wealth. Be safe or be safe. Just my two cents here. Cheers.
