So obviously the source of the error is one or more third parties, not Microsoft, and it's obviously impossible for Microsoft to be responsible in advance for what other people claim to license.
It does make you wonder, however, if Microsoft ought to be responsible for obeying a type of "DCMA takedown" request that should apply to ML models -- not on all 32,000 sources but rather on a specified text snippet -- to be implemented the next time the model is trained (or if it's practical for filters to be placed on the output of the existing model). I don't know what the law says, but it certainly seems like a takedown model would be a good compromise here.