I would be wary of referring to "Oberschule" as "college" - a word which refers to post-secondary education. The example even notes that this is from a school-leaving certificate to be presented for admission to university (aka college). Now I don't know if such trade schools might also be called "colleges" in the UK, but in the US at least you would not (to my knowledge) call anything a "college" that isn't the same qualification-wise as a "university". That's why I'd avoid ambiguity and leave out "college" altogether. That's also why I've suggested "pre-university for the "Oberschule" bit rather than "upper level" or the like to avoid ambiguities, as "upper-level" etc. doesn't tell us if it's upper level high school or college/university or what. (I'm also keeping in mind that the term is being used as an umbrella term for "Berufsoberschulen" and "Fachoberschulen" as in the FOBOSO, which I'll repost here in case that's helpful in fleshing out these concepts.)