if your are not familiar with HTML-Code ... it is maybe too difficult

I describe the steps to get a direct link to a user comment
in the FireFox-Browser

sample-link is: http://www.duolingo.com/comment/209688$comment_id=209846

the only difficulty is to get the "comment_id"

the next three pictures are describing the steps

(01): first you have to select the text
important: you have to select the Reply-Text of the previous user comment
... to get the nested-comment-id

(02): select the menu ("Auswahl-Quelltext anzeigen")

(03): search ( CTRL+F ) id="nested-comment-

(04): this number is the "comment_id" ... here ( 209846 )

(05): to be sure that's the right number
scroll the window until the link of the user appears
[a href="Katherle" title="Katherle" ...