The Debugging Challenges on this site are way too easy.
I think you should give no more than 5-10 points for each of them.
They are only very easy if you know the language in question very well ... and then the same would go for any challenge on this site (eg electrical). If you haven't coded in that language, then they take a fair bit of research ... worthwhile research, because the bugs are usually fundamental ones. For me, the points given seem about right.