Since speed is different from user to user, it was not included in the target possibility.
For example, 30KMH on a trainer may be 500W but 30KMH on another trainer could be 100W of power.
I wanted workouts to be the same for every users, so that they can be shared easily.
If you girlfriend has a trainer that has a Power Curve in the software, you can get Power data from speed data easily (just need a Speed or Speed Cadence sensor which you already have it seems). Let me know if you need help to set a Power Curve.
Cheers and thanks for the feedback! Have fun :)