It seems that is not possible today (or in a complex way?) to display in notices information stored in additional fields defined in admin/additional-fields.pl It could be nice to add this feature, in the same spirit as https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=30657
This could be useful for our libraries as well. We are sending messages in three languages, but currently the library's name can't be printed in the correct language. If these additional fields would be available in notices, we could add translations to library names with additional fields and then use those in notice templates.