Do not confuse inherent chaotic unpredictability with converging averages of larger samplings. These are quite different things!

Its possible to develop an ever more precise estimation of average ENSO-QBO periodicity, and still not be able to precisely predict inflections. Of course QBO is more periodic, but still seen to express chaotic statistics.

Here is a mother lode of ENSO Chaos science with a mention of "forcings from ... orbital variations", without specifiying a reference from the vast bibliography:

"Previous studies have revealed a wide range of ENSO responses to forcings from greenhouse gases, aerosols, and orbital variations, but they have also shown that interdecadal modulation of ENSO can arise even without such forcings."

ENSO Modulation: Is It Decadally Predictable?

Wittenberg et al 2014