Can you send me a link to the journey planner results? There is no specific way to contribute improvements to the results, best way for now would be to leave feedback through the form in the title bar of the new website.
Edit: You also might get some mileage out of setting your walking speed to "Fast" and selecting "Routes with fewest changes"
Edit: You also might get some mileage out of setting your walking speed to "Fast" and selecting "Routes with fewest changes"