Jan,
This would be quite an undertaking to get to the right information.
You’ll have to rewrite/ expand the excel importer to get to the cellstyle information.
See here for a short discussion on the same issue in grails: https://stackoverflow.com/questions/10425473/reading-cell-styles-along-with-data-excel-sheet-reading-using-apache-poi/10425538
Might give you an idea on what to do (look at the link for cellstyle in POI specifically)