For anything vaguely technical, I use the English term. I don't feel comfortable in any other language, no matter how well I speak it. It just doesn't sit right with me to use eg a Danish term for density, or power, or eigenvalue, or anything programming.

Part of it is that even though I might know the term, it won't be long before I need to bring in something where I don't know the term. At that point I'll be inventing a local term, when I know what the English term is.