Really, simply to add "mul" to the list of included languages should be sufficient (in the double significance of "no specified language - multiple languages"). The "old" prefix would be perhaps better, since it's already in use into Iwpage transclusion. English could be linked to "mul" as default language for translation issues of interface. Is this so terribly difficult? Is there really a hard techno issue, or the whole matter is mainly a matter of "policy"? The latter case would be very disturbing.
Alex