Hi, welcome to LQ!
I can't see a single line w/ a backslash in there when I manually do your wget
& grep here ... I'd be surprised if that sed worked on anything at all.
grep -oE '/user/[^/]+/traces/[0-9]+' traces |sort -u
P.S.: I renamed your thread to something I felt was more sensible than
"question", and I fixed your code-tag....