thats not how this works

decidability does not distribute over pointwise question asking on sets, or if you believe it does, show us the proof.

Telling if an EML(x,y),1 constructed expression is identically 0 is in the gray zone, as far as I can tell, it has neither been proven decidable nor been proven undecidable.

Nevertheless regardless of decidability the authors clearly show the multipoint sampling/testing is a decent filter, and the shorter resulting expressions have been proven correct in the results for the construction at least.