I haven't even gotten a single successful guess on task 2
Well, this was tricky, my explanation was not quite right how and when the second task is chosen, but as an intelligent human you should have discovered this

I updated the webpage, now it explains it better. I can't show the current task, because in the challenge the AI program wouldn't see it either. But maybe I should add a checkbox to do this for us stupid humans

This is the second task:
https://github.com/general-ai-challenge/Round1/blob/master/src/tasks/challenge/round1/challenge_micro.py#L283Translation: for all ASCII characters you have to answer with the same one random character, same as in the first task, but for the characters !":?.,; and space you have to answer the question character.
Looks like the first task can occur multiple times at the beginning before the second task is chosen. This task scheduler is used:
https://github.com/general-ai-challenge/Round1/blob/master/src/core/scheduler.py#L121Edit 2: I checked the spec [PDF] (spoilers!) and the task described in section A.2.2 doesn't seem to match what I was seeing.
Looks like they have some problems with formatting in the PDF, the space character has not the same fixed width than the other characters. But it seems to be the second task as I described it.
But the tasks are just examples. They could use a complete different set for the non-public tasks when testing the AI programs.