Creators should have an
opf:role attribute to indicate their, well, role. The OPF standard suggests the creators should be ordered for display, but IMO you would be better off specifying each creator's role explicitly.
eg set opf:role="aut" (for an author) or opf:role="trl" (translator)
There are lots of other possible values for role.. See
https://idpf.org/epub/20/spec/OPF_2....l#Section2.2.2 and
https://www.loc.gov/marc/relators/relacode.html for the full list of values.