Here are some options to consider:
- Have the unit correct itself with Automatic Routing turned on. As you ride, take those roads that have bicycle signs on them. The unit will recalculate the route to make sure you are still going in the general direction of your destination. This will not be most optimal route, but will improve on earlier selection.
- Supplement the first option with another map on smart phone or paper map. Use this other map to get a general idea of the best routes back home. Take these routes as you ride. The unit will recalculate to give you detailed routing & turn prompts, while making sure you ultimately reach your destination.
- Change the map set. Download OpenFietsMap map sets for example. These are free. You can just experiment with them. I understand that Garmin is using them, or some version of them, on their Edge Touring unit.