Hi!
I just figured out how to do this, as we're running a multilingual
application, and it's been recently discovered that a contract was
signed, implying that we can provide french reports - before they
asked us!!
Flip side is, that this is all with Oracle 10g install. On the plus
side, it's actually pretty easy:

1) Open Reports Builder.
2) Go To: Tools/File Conversion
3) Convert reports desired to ".rex"
4) Load .rex reports into Translation Hub
5) Run through Translation Hub
6) Convert files *back* to ".rdf"
7) Open reports in Reports Builder
8) Add line of Code, in AfterPForm or BeforeReport triggers:
a. "SRW.DO_SQL('alter session set NLS_LANGUAGE = ''FRENCH''');"
b. of course, replace ''FRENCH'' with
whatever language you're using.
c. the quotes are ALL single quotes.
9) Recompile and save reports.
10) Upload to where you'll use them!

These instructions have been written assuming that the application has
a base language, and a secondary language, and that there are actually
two different copies of each form on the application. You would store
the french reports with the french application. Or whatever the
language is.

Hope this helps someone!!