Google do a very nice translation add-on for webpages. With the international clientel of Gramps, it may be a nice touch to offer all users the ability to translate postings which are written in a foreign language.
There’s a Microsoft Translator & Google Translate add-on for Discourse. But it drives a per-translation fee structure.
That might just be another cost of breaking into a new market for commercial products. However, adding overhead is not viable for Open Source projects.