Have been slowly catching up here, learning a lot. On the other hand, I immediately bring to bear extra applicable background, like topological matter and general geophysics knowledge.
"Precise cancellation of Coriolis along the equator" is a crude rather un-physical assumption, given so many exception factors. That's "(finding something) wrong with (primitive LaPlacian) derivation".
Again, ENSO and QBO Equatorial Belt wave-guides are anything but perfect Topological Insulators. Nor is geophysical topological robustness against perturbations helpful to the hypothesis these Earth-rotation dominated systems are so sensitive to lunisolar tides.
It seems as if the major geophysical oscillations are all only metastable Helmholtz resonances, that start to go chaotically haywire when they drift near a major state transition. This is a very different kind of theory (dynamical-chaos) from long period forcing conjunctions by multi-orbital periodicity.