My German speaking friends -- I am pondering how to make polyglot a tool I work on. As input it takes things like: Given this starting condition When some action is taken Then some result occurs The Given/When/Then are keywords. Would Gegeben/Als/Dann be acceptable in German?

"Gegeben" is not used as naturally as "given" in English. It feels a little off but I can't think of anything else. For "When" I'd use "Wenn", which is its literal translation. "Dann" is good. "Wenn ..., dann ..." sentences are very common.