Here is an analog gedankenexperiment regarding the nature of long-period geophysical oscillations and supposed short-period tidal forcing.
A violin string resonates at its major harmonics when driven by a rosined bow. The rosin energy input is at far higher frequencies than the musical notes. There is both the direct ultrasonic forcing by the rosin, and bulk sonic output, but no physical requirement that rosin frequency be an exact harmonic multiple of bulk frequency (frequency-forcing). Rosin frequency is in fact stochastic, a bit of added "warmth" to the resonant violin tonality.
Just so, there is a short period tidal-energy input to long-period geophysical oscillations, whose major harmonics are excited at resonant long-period frequencies. Tidal inputs cannot act as regularly as the pure orbital mechanics, because they interact chaotically (asynchronously) with rotating continental terrain, current and weather transients, and solar cycles. There are also other major energy inputs, like Coriolis momentum into the QBO, to further muddy the tidal signal.
We may surmise geophysical oscillations are sensitive to continuous (non-integer) spectrums of input, just as a bowed plate with sand displays Chladni Pattern state transitions. We can assert quasi-periodic forcing exists, if not ideal periodic forcing.
All this is at best "strong analogy", not "proof". Better validation remains open to proper data and calculation.