@new.user I have similar questions, I’m a brand new user also.
there is a link in the helps page https://maps.google.com/roadmapper/u/0/help
to this forum post Frequently Asked Questions: Road Mapper
so it suggests that if a road is incorrect, then it should be fixed.
this one was a good one also:
My follow up on this would be that if I ignore fixing a road, then the challenge will not be accepted?
All the initial guidance seems to be about adding new roads rather than fixing them. It was only when I saw the FAQ post then I see the mention of fixing roads. But it sounds important.