At least, that's always been a reason that I've suspected singspiele aren't performed more often outside their country of origin.
I agree with you here, but there is a way out - which is to translate the spoken dialogue! I am more than certain the original author would have wanted their work understood by audiences, and not performed in an entirely alien language which they don't understand! :))
I've seen Magic Flute, Seraglio etc performed with translated dialogue - and it works excellently. There is no reason not to do it! The only exception, maybe, would be recordings. There the dialogue is almost always recorded by native-speaking German actors in any case :)
There is also historical precedent for translating. When Dittersdorf's DOKTOR UND APOTHEKER was premiered in London (about 3-4 years after the Viennese premier) it was titled DOCTOR & APOTHECARY, and performed entirely in English :)
