The report window has a section in which you are supposed to copy the chat that went on if that is what you are reporting.
They'll obviously check the whole incident itsself, but it helps if you actually DO post a copy of the chat in there

As it stands, you can only report if you yourself get harassed, not for others.
Based on the way you reported it, I can see how they would understand it as "concerning other players" and not you.
Although the "feedback" response is completely off-topic and kind of rude. You clarified your report and they treat it as game feedback? Wtf?