Here are a few ways you can attempt to find translations:
1. In OskiCat, do an author search and then limit the results to English by clicking on the MODIFY SEARCH button. To find lists of books that have been translated into English, use the Advanced Keyword Search. Change one of the search boxes to Subject, and enter the language, bibliography, and translations into English.
2. Search in Index Translationum. Updated by UNESCO's Sector for Culture, this database contains over 2 million entries for books translated and published in almost 150 countries from 1979 to present, though for many countries it is not up to date. It is not comprehensive. The library also owns the print edition from 1932-1985.
3. Search in Worldcat. Choose Advanced Search so you can do an author search and at the bottom of the form you'll be able to limit to English (or another language).
For literary works, you can also try The Oxford Guide to Literature in English Translation and Literatures of the World in English Translation.