I think it might be a good idea if a musical written in English could also be re-written in the native language in which the story takes place.
*I have actually seen the French version of LES MISERABLES (based on the Cameron Mackintosh production) in Paris in 1992 and it was very good.
*Phantom of the Opera might sound equally good in French
*And maybe Man of La Mancha in Spanish
*And maybe West Side Story could be bi-lingual...and likewise Aspects of Love