A few items which appear to be inconsistencies.
When parsing FLAC, ID3, or MPEG-4 files , a remixer found as a Remixer field in a PERSONNEL tag or in a separate REMIXER tag will be processed correctly. However, when parsing ID3 files, TPE4 frames should be processed as Remixer. TPE4 is pretty much universally used to store a remixer in ID3 based files. Other ID3 ‘credit’ type fields such as TCOM, TPE3 and TEXT are parsed correctly. I’m not sure why TPE4 should not be parsed as well.
The original release date parsing for ID3 based files is quite complicated. It seems as if TDRC, TDRL, TDOR (ID3v2.4) and TORY (ID3v2.3) will all be used as Release Date. I’m not entirely clear on how priorities are determined if more than one field is present. In order to get Original Release Date to be recognized, a TXXX frame named ORIGINALRELEASEDATE must be created. Clearly TDOR and TORY should always be parsed as Original Release Date, as again, that is a far more than common usage model.