Reverse saved course

Yes, but in this case you must stop recording while driving.

If you want to reverse a track mid ride, then you can just navigate to the start using the same path (EDGE allows that) or load the track from the Edge memory that is already inverted...You cannot get any stuff from the cloud unless you stop the activity...

If I have the track on GARMIN CONNECT, I sometimes have two versions... the regular version and the reverse version, that way I can test the tracks on both directions...I works better for MTB than road.

Why invent? There should be a "reverse direction" function. That's it. 

With the GRouteLoader CIQ widget you can download a course from Garmin Connect or Ride with GPS without ending your current activity. If the course fit file is on your phone you can also use it to download via the Gexporter Android app

Note that the courses have to be public to be downloadable by GRouteLoader.

GRouteLoader can also download from the Gexporter Android app.

"Why invent? There should be a "reverse direction" function. That's it."

What do you do until then?

I stop driving record and upload the changed course again.

"Is the introduction of this function so complicated?"

It doesn't exist at the moment.

It doesn't make sense to give people providing a work around a hard time.

This forum isn't reliably read by Garmin. It's mostly a user forum.