…although, to be fair, I think all languages have something that is difficult to learn. Swedish has the extra letters ö,å,ä which affect pronunciation, and I can never remember, because the same word can have o as a noun and ö as a verb/the plural. I frequently get it wrong.
In Swedish the work for marriage and poison is the same (gift).
I love that
I don’t quite agree with the fact that English is a particularly difficult language to learn. I think that all languages are difficult if someone wants to master them. Unfortunately very few people know and use all the subtilities of their mother tongue, let alone foreign ones!
For instance when I hear or read French people, I often think that they only use a little percentage of it in terms of vocabulary and some of them even ignore many grammar rules.
And the same concept applies to most languages unfortunately.
You are correct of course. Languages I pesonally would find most difficult to master are Arabic, Chines, Japanese, and Thai, because they are unlike anything I know. But in themselves they are probably no difficult to master than any other language.