It's a bit more complicated at times, and it's hard to know if the label skipped QC, chose to keep the technical claim because of marketing over complaints, or chose to trust the right holders' technical claim despite A/B comparisons clearly showing they shouldn't have.
In the case, for instance, of Five Graves to Cairo with MoC, it seems like Universal insisted that what they gave Eureka was a 4K something master. The issue to me is more with people at Eureka seemingly thinking this could have been the case while the master they were given looks like a battered 20 years old one and nothing like anything more recent, let alone done in 4K (or at least scanned in 4K), but this means however that people at Eureka DID check to some extent what they were given.
It's hard to know if this has been the case for Alfredo Garcia at Kino, but in any case, I'd deem the best thing would at least be to drop the technical claim if you're unsure of what you're getting, but on the other hand, how many people will realise this isn't a new 4K master ? I've seen people raving about what turned out to be a SD-upscale, so it's clearly not as if most consumers were acutely aware of these things.
However, true enough, right holders' materials are to be checked and compared no matter what because you just can't trust them 100%. Whether for Eureka then or Kino now, a simple A/B comparison allows to know if you've indeed been given a new master or something that reaaaaaally looks like this older master and not really like this new one. I've been however told that indeed, not every label does such comparisons, sadly...
I'm quite certain their workflow is now smooth enough that such an issue would be corrected before the discs are pressed and not after like it was for Sinbad.
Kino delivered on this one because they were the one doing the 4K remaster, ie masters of what they were doing. Eureka was however in a technical licensee position, ie dependant on what they were given. However, when placed in the same situation of being dependant of what they're given, Kino seems to have a much looser QC.