Updating through the third party websites isn't a good option for two reasons. First, you'd have to update hundreds of address pins for the fix to be effective. Second, there's a review process for each update, which may not happen for months, and if moving the pins are only beneficial for Waze purposes, but not for the other subscribers, it's never going to happen.
Yes, it's a good idea to update the internal Waze addresses, but as of now, those addresses aren't even referenced. It should work sometime in the distant future though.
The only real option right now is to remove the alleys, but only if routing to them is undesirable 100% of the time, like the example I posted above.
Via my iPhone 4S.