Your tip does not work:
"As both quién and quien are translated by who, it is sometimes difficult to know which one you need. If you can substitute who by the question words (interrogative) "which person" and the sentence still makes sense, then you need quién (with an accent). Note that this tip is not about making a "good translation" but just about identifying whether you need quien or quién."
This is false.
I am a native English speaker and this rule is inconsistent.
You need a better clarification, an option to ignore this "lessson"