I’ve been working on the Releases of a defunct label.
The only sources I can find for Release dates (almost always just a year) are things like unsourced metadata at Discogs and Allmusic etc pages for each Release.
I have no reason to believe these years are anything other than the “P” &“C” year from the Release coverart.
Leave it, remove it, leave and annotate, remove and annotate, something else?
(These dates yyyy/yyyy:mm/yyyy:mm:dd are unfortunately used to order the Releases in nonintuitive and catalogue-number-sequence* destroying ways on the page listing the Releases of the Label. And so have a negative effect on UE.
Except for this I would probably not be at all interested in the issues of Release date validity.
*Whilst Release dates seem very difficult to verify or discover, catalogue numbers are very oftern featured on coverart. Though I do admit that the multiple ways that catalogue numbers get altered and deformed on various music databases is a surprise.)