Which languages you think are difficult depends on the person.
Which languages you consider to be difficult differs from person to person.
How difficult you think a language is different for different people.
「何の言語が難しいと感じるかは人によって違う」は英語に訳すとこのようです。
Which languages you think are difficult depends on the person.
Which languages you consider to be difficult differs from person to person.
How difficult you think a language is different for different people.
それそれの言い方があります。
「〇〇は人によって違う」はこのようです。
〇〇 depends on the person.
〇〇 differs from person to person.
〇〇 is different for different people.
What languages you think are difficult depends on your native language. も言えるかもしれません。（何言語は難しいは母国語によって違う）
ご参考までに。
Different people think certain foreign languages are difficult depending on who they are.
この場合、次のような言い方ができますよ。
ーDifferent people think certain foreign languages are difficult depending on who they are.
「異なる人が特定の外国語を難しいと考え、それはその人たちによる」＝「何の言語が難しいと感じるかは人によって違う」
ご参考まで！
アメリカ合衆国 
カナダ 
