TOD
I cannot match DR Elmore's knowledge and comprehensive lists of good English translations, but I was taught that composers -- in general -- wanted their works to be understood and appreciated, and were surprisingly open to their operas being sung in a region's own language.
But quality and purpose of translation really matters, and I was also taught that those Met ones such as Cosė, Fledermaus, and Hansel and Gretel were among the very best singing translations. They are still favorites of mine. When just studying an opera, you want a literal translation (the Verdi and Puccini ones by William Weaver were the bible for us in school). But when performing one, it needs to meet different criteria while hopefully being as true to the original as possible.
This really makes me want to take out those recordings.