Yes, the movie is meant to be watched with subtitles for the foreign language scenes — and those subtitles are essential to the plot.
Here’s a helpful, concise post you can use for a forum, social media, or a quick answer: Does Inglourious Basterds have subtitles? does inglourious basterds have subtitles
Yes — but only for the non-English dialogue. Yes, the movie is meant to be watched