I answered "more or less" and it was right, is that translation less literal, and more about translating two commonly used sayings from each language? I say this thinking that a literal translation would at least reverse the order, and say "less or more" which of course could then confuse with the English saying "less is more"...
Sometimes the program seems to want a literal answer, and sometimes it seeks a colloquial answer. To see "mniej wiecey" would seem to want the literal answer "less more" in that order, like one, two, three, four, five. I know you have to alter the computer program to add a lot of words to match how things are spoken in English. But this seemed to be two random words of numeric value that just mean "less, more". Is this a real phrase in Polish for "more or less?" It also seems to be it could be more of less. Or would that be a different case?
According to https://en.wikipedia.org/wiki/Polish_morphology#Numbers_and_quantifiers , both "mniej" and "więcej" are invariant, so even if a different case were to be involved, it wouldn't show. Going by the comments above, "mniej więcej" does indeed mean "more or less"; it is not a literal translation - Polish and English are sufficiently distant from each other that not every phrase is a literal substitution.