The problem is that you seem to lack any intuition with respect to data analysis or signal processing. Of course there's not a fixed period when it is caused by a periodic impulse magnifying an underlying tidal signal. The impulse is on semi-annual cycles so that what we see is essentially the strength of the tidal modulation on these impulses, which when viewed **at a distance** shows the 2.37 year period.


The solar and lunar periods are incommensurate (top 2 panels) so that the periods are not strict and may dance around a bit depending on the triggering factors. But when the two are commensurate, such as the nodal and solar pulses coinciding as harmonics (bottom panel), the cycle of course lands on the pulse.

This is well-known in tidal analysis circles where the patterns aren't fixed on strictly periodic dates either, so that tidal predictions (such as dates of king tide occurrences) are still supplied as look-up tables and not some formula that you seem to be expecting. Sailors and ocean dwellers may not know all the math on this but certainly they have gained some intuition how this works, which you seem indifferent to, or worse, belligerent against understanding.

And you know what? I also don't care to be playing any more of these got-you-games, where you claim orbital resonance when I am clearly talking about resonance in a fluid wave equation. So just chill a bit.