Well, you found the forums, so that's a start. A lot of good info to read in here that will help you understand how Waze works.
Next, go to the Wiki in the support section and read on how to use Waze and edit.
Then you can go to the update map. Open a Update Request and see how they appear. It is often difficult to see or figure out what the error was. Wrong directions to a location, wrong turn directions, etc...
Once you read the Wiki and watch the videos, you will see the directions to a location aren't from Waze per say, they are outsourced to Bing. You can put in an address and when your results come up on your phone, look to see what source it comes from. You can pick a different source like Google, your contacts, Bing, Yelp. I have looked at the map for a location to make sure it is right. If the location is wrong from a source like Bing, you can go to Bing maps and report the problem to them.