As you have noted, the Workout app does not record either distance or a route map for Other workouts *.
You may find that a third-party app meets your needs for recording roller blading workouts complete with distance data.
For example, Runkeeper:
Runkeeper—GPS Running Tracker on the App Store
- Available activities include Skating:
- Setting up Runkeeper for Apple Watch:
* To record and label skating workouts - including roller blading - using the built-in Workout app, record your workout under "Other". This credits one minute of Exercise for each full minute of the workout and Active calories at a rate equivalent to a brisk walk or based on data from the heart rate sensor, whichever is higher.
To record the workout as "Skating": when ending your workout in the app, tap on the menu option for "Name Workout" and select "Skating" from the list of activities:
Work out with your Apple Watch - Apple Support