Kant vs Nietzsche

That is pretty much right, Erik, although i.e. the differences between two Germanic languages are not as large as the differences between i.e one Germanic language and one Romanic language. Very huge are the differences between one Indogermanic language and i.e. one Afroasiatic language.

To know i.e. the language of the Koran is very useful in order to understand the Muslims and their religion, their “spiritual exercise” (Peter Sloterdijk).

To study Kant does not necessarily mean to invest “thousands of hours”, but you need more time for studying Kant, if you do not know the German language, than you need, if you know the German language. So it is a huge adavantage to know the German language when it coems to understand Kant, his country, his culture, and - last but not least - his philosophy. This does not only concern the time you need or other special aspects but also general aspects.