I have just read the mail, but i will answer here
It's not a bug, it's just how the exponential scoring works.
Only a few challs means that the big points only come when you have solved a lot %.
Take a look at the
ranking page for reversing.kr to get an impression of that.
If the settings applied to reversing.kr seem to harsh we could lower the exponential effect a bit, but i am not sure of the difficulty on the site, and the default settings in use are probably OK.
EDIT: And please use the correct values for challcount. If the scoring curve seems to harsh we can adjust it in wechall settings for a site.
Greetings
Gizmore