Yes, mapping is the issue here. 'year' (date?) is a rather complicated and flawed phenomenon in tagging. It will depend on the ID3 tagging version, and on the implementation of the software or player what tags are read and written for that, and even what they are called.
These are all existing 'date' (year?) ID3 tags: TDAT, TIME, TRDA, TYER, TDRC
My question is if it is possible to have a column only showing the TYER tag.
I have been trying this with custom and virtual tags, but can't figure out if it can be done.