I know mismatched Workout Levels between the Web and TR App was a known issue, and may or may not be solved. You can email support@trainerroad.com so they can check.
On your substitution goal, the best approach now is to open the TR app, open your planned workout, and activate the “Alternates” tab. There you can set a desired Duration or Intensity, the quickly offers a filtered list of workouts with the same goals of your planned workout. You can pick your desired substitute and Replace it right there.
Here are some screen shots showing the intro of the tool.