As you say, it was certainly not demonstrated as nothing it predicted was found to date -- no particles that could comprise dark matter, no siblings or cousins of the Higgs boson, no sign of extra dimensions, no leptoquarks, no supersymmetry particles.

Also, even cellular automata interpretation is arguably a stretch -- e.g. broken Lorentz invariance (though there are workarounds that restore it), but, more importantly, it implies superdeterminism (lol).

However -- both, holographic principle as well as cellular automata, are still very useful concepts IMO. They certainly demonstrate that the observed (and demonstrable) phenomena that need to be accounted for do, indeed, have solutions. And I'm fairly certain that a skillful mathematician would be able to incorporate them into more "sane" QM interpretations (moreover, without their implied nonsense).