I would suggest to have (at least) the following lists in the information boxes, resp., copyright statements:
Author(s): (lists all creators role="aut"), Contributor(s): (lists all contributors role="aut")
Editor(s): (all creators with role="edt"), Contributor(s): (all contributors with role="edt")
Applet(s): (all programmers of applets, which for that purpose need to be encoded as such, cf. issue AMAuthoring-33)
Translation: (all creators with role="trl"), Contributor(s): (all contributors with role="trl")
... maybe even others
In the copyright boxes, the last line should only appear if the xml:lang of the author differs from the actual language, in which the item is displayed, and in this case, only the translator for this language should be shown, not all translators for all languages. (Of course, this is different in the general information box for some book, where all translators should be mentioned.)
In addition, only those entries should be shown that really apply, i.e., if the item (or book) contains no applet, then this line should be missing, and also if there are no contributors, then the "Contributor(s)" part should be missing.