hi, really, for Admin should not be needed 'cause usually the Admin can manage everything in English and if he wants can translate with calm... but
we are in 2014, this software has a truly good potential but lacks of modern features which would make it definitely strong. Unfortunately i know well PHP and not PERL, otherwise I would have helped more...
to me it's not possible to do 7-8 steps to change language and finally even reload the page... the users could find it boring
IMO it would need to:
better linking, so direct URL to language e.g. for spanish
and/or country flags (inline or dropdown etc...as you want) for desired countries choosen by Admin on the Virtualmin user homepage
session that immediately changes the language without those many steps
better translation support, e. g. wbm translator doesn't distinguish between Admin and User interface and puts all the translation strings together. This is difficult for Admins which have to translate the correct strings for users only, instead of the whole interface... this way Admin often can't know what are the priorities... Furthermore, when you translate UTF-8 files with wbm translator, instead of the correct accented and special chars it puts foreign characters inside (e.g. if you see it by notepad++) and you have to do double work to convert again.
hope this helps