If there isn’t an English translation for a book you want, JewishGen probably will accept donations to fund the translation; there are multiple translation and indexing projects that they fundraise for at a time.

Slightly off the subject of Yizkor books, there are also other nonprofits that are affiliated with JewishGen, such as LitvakSIG, JRI-Poland, and Gesher Galicia, who also fundraise for record translation and indexing. I’ve been working with LitvakSIG & Maceva, a Lithuanian non-profit on a project.