I'd say that Chinese is honestly a harder language because it is filled with too much idiosyncrasy. I think most Chinese people cannot decipher the meaning or pronunciation of new Chinese words they've never seen before.
And if they've forgotten how to write a character, then they are doomed without outside reference. I can use a word in English I've only seen or heard once in a novel event, and have a hope of using it passably.
Even looking things up in the dictionary is hard... for Chinese people. I've seen Chinese parents pride themselves on how skillfully their children use the dictionary. That's because it's hard and worthy of pride; the radical system is so random and unnecessary from an outside view. Chinese is worthy of the reputation that perl has had, and for the exact same reasons: it's capriciously idiosyncratic and ruthless to non-native speakers.
I'd also note that non-native language acquisition has been looked at by the US military, and I'm sure across the world, and I doubt that all languages are rated equally. I'm quite sure that Arabic and Chinese rate as very hard languages.
I suspect that english has been made easier for non-native speakers by a rich recent history of english being spoken by non-native speakers (particularly in America). This may have broken down expectations about the language that native english speakers have.
For example, a native english speaker will not have much difficulty at all when they encounter an Russian who speaks english as a second language and frequently miss or misuse articles. Although the native Russian speaker is technically using the english language incorrectly, native english speakers have adapted to expect and tolerate a very high rate of errors. This lowers the level of language perfection that is necessary to effectively communicate in english.
Speakers of languages without this sort of recent tradition of non-native speakers may find grammatical errors more jarring, because they have been exposed to them less often.
And if they've forgotten how to write a character, then they are doomed without outside reference. I can use a word in English I've only seen or heard once in a novel event, and have a hope of using it passably.
Even looking things up in the dictionary is hard... for Chinese people. I've seen Chinese parents pride themselves on how skillfully their children use the dictionary. That's because it's hard and worthy of pride; the radical system is so random and unnecessary from an outside view. Chinese is worthy of the reputation that perl has had, and for the exact same reasons: it's capriciously idiosyncratic and ruthless to non-native speakers.
I'd also note that non-native language acquisition has been looked at by the US military, and I'm sure across the world, and I doubt that all languages are rated equally. I'm quite sure that Arabic and Chinese rate as very hard languages.