Is this an accurate summary?

43 out of 147 = 29.2% success rate for 1900-1973
17 out of 70 = 24.3% for 1974-2007

this matches the odds for the whole interval being 60/217 = 27% for 1900-2007.

If the chances at random are 22.1%, I doubt the success rate of 24.3% over just 17 hits has much significance. So the syzygy prediction is not showing success since the prediction was made, certainly not enough for anyone to take specific preparations in any one of the supermoon time windows.

One interpretation is that Berkland examined many patterns, maybe several hundred, and retrospectively found one with 97% significance (there should have been several at random in a hundred guesses about how to predict quakes), and the prediction method is not proving to work.