If the problem requires science, I think in English because most of my relevant university education and R&D was/is in English and thus most of the terminology

If the problem requires science, I think in English because most of my relevant university education and R&D was/is in English and thus most of the terminology I know. If it's business-related, I think most the time in German. I draw causal diagrams and sketch in Haskellesque pseudo code.