This feels like a bug to me:

Comments on journal entries can be rated up just like posts within threads. When that happens you get the usual green +3 notification and a hyperlink in your reputation history. However for journal comments neither the green notification nor the record in your rep history actually link back to the comment in question (they just link to the homepage). It is therefore hard to work out where (or why) you were rated up - which is something I like to know generally.

It works fine for thread posts though: Takes you to the post that received the rate.

This might be a bug or a software limitation - hard to say(?)