It allows selecting multiple languages, but it's not clear and setting multiple is fiddly - most sites use multiple checkboxes instead for this reason. Anyway, if you select Undetermined, English and whatever else you're happy to see, you'll see a lot more comments (and posts, probably).

Edit: to select multiple, hold control while clicking/spacebarring to add another.

It should have two language settings - those you might post in (for the dropdown on making a comment/post) and for those you're happy to read (I'd just set it to all, since I can always translate anything that looks interesting).