Comment by jandrewrogers

On a superficial level that seems like a roughly correct ranking in my experience. On the other hand, I picked up one of the category 3 languages pretty easily. I think some of these are more "weird" to a native English speaker than "hard" per se.

The aspects that make languages difficult for a native English speaker vary quite a bit with the language. I would expect individual experiences with the languages to have high variance as a consequence.