My only thoughts are the usual ones: to me the analysis chain is not really the best tool to do the job of cleaning up faceting labels?
These tasks typically dont require tokenization and work on whole values, and may require stuff like extracting values from one field into another. While its true you can do some of this cleanup (casing/trimming,etc) in the analysis chain by (ab)using the fact that fieldcache uninverts indexed values and using keywordtokenizer and using filters like this, its not very intuitive, and you can't do all of it, whereas using something like solr's updateprocessor chain might be a better place to have this support. There is already overlap, e.g. it can trim field contents as well.