It appears that Airtime 2.5.1 uses the ID3 tag 'label' for the record label - and you must enable it in the web interface by clicking on Show/Hide Columns in the web interface and then selecting 'Label' in the drop down list. Many people use the 'producer' tag for this, but that tag does not appear to be supported by Airtime.
you're right, bachic airtime should recognize any id3tag and use it in library. the metadata for "publisher" can not be displayed correctly in airtime yet. you could create a ticket on bug-tracker dev.sourcefabric.org fg
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