Wikipedia says that the natural abundance of Xenon-124 is 0.095% = 1/1000. Adding that correction I get a few decays per day that is more similar to the data reported in other commit that is 126 events in 177 days.

Edit: I think I'm missing a ln_e(2) in the calculation, but it's only a 30% more or 30% less. It's not a huge change in the result.

article says “1,300 kilograms (2,866 pounds) of xenon isotope”

not sure if that was intentional..

The other article didn't have the exact number, so I used the number of Wikipedia that says something like 3.6 tons in total and 2tons inside the measurement part (or something like that).