A 7.1-magnitude earthquake hit off the coast of Chile on Sunday, the U.S. Geological Survey reported

I think the 188-day cycle theory should be revised as more of a range. IMO, the natural world appears to prefer variation within constraints, whenever there is a real pattern involved.
I don't have the capacity to do the math required to support a range of days, rather than the specific semi-annual cycle proposed by the evidence presented, but I suspect that, if there is anything to it, a pattern of waxing and waning extreme seismic activity could be charted.

Maybe someone with more knowledge and resourcefulness - and who know what they're looking for - would be able to test that.