This is no solution, just an explanation: WordPress currently doesn’t have taxonomy meta data. You could add a stand alone table to add meta data there. Anyway, it’s not recommended to add your taxonomy/category/tag meta data to the options table as this one wasn’t made to get JOINed to do meta queries by it. My personal recommendation would be that you simply add another taxonomy that has your meta value and as well link this one. This would allow you to do default a tax_query by two taxonomies and their terms.
