You can fix the elevation problem with the house. Evict your household to the clipboard in Edit Town, or temporarily have them move to a different lot in the game. In Edit Town, save the house to the library. Then bulldoze it.
Open the cheat box (ctrl+shift+c) and type TestingCheatsEnabled true, then Enter.
Open the cheat box again and type SetImportedTerrainElevation followed by -. Since 1 seems to represent the size of one of the squares in build/buy mode, if the elevation is slight, you need a smaller increment, so start with something like -.5
After you do that, place the house from the library. When you look it over before you accept the placement, take a good look at the terrain in front of and around the house. If it's still elevated, don't accept. Cancel out and try the cheat again, using a slightly larger number. If it's dipping below the level of the road, try a smaller negative number instead. Keep working at it with different numbers until it's sitting flat on the lot. Sometimes you have to go ahead and accept the placement and look at it in build mode to find out if it's level. If it still isn't you need to bulldoze it and try again.
If you do this and nothing happens at all, try typing the number as -0.5 I honestly don't do it enough to remember whether it should be done with or without the leading zero, but I do remember that if nothing happens with it one way, the other way will make it work. So maybe if -.5 doesn't work you should try -0.5 before trying different numbers.
When you're done, remember to open the cheat box one more time and type in SetImportedTerrainOffset 0.
Now you can place your household back in their house.
I have never had the problem you've described, so I don't know if fixing the elevation issues will fix the problem. It probably won't if the elevation offset is small. Hopefully, someone else will have some ideas of what could be causing the routing issues.
