I have reverted the entire changeset. There were some conflicts with the server data, but I hope I have resolved them correctly.

This must be a mistake, but I have no idea how it happened. :-(

Can you recommend a procedure for how I can most easily reset the one-way changes to highways?

I only know how to reset the entire changeset. But that would mean all the desired changes would be lost.

I would be very grateful if you could help me with this!

I have not edited the direction of highways. If I notice that waterways are flowing in the wrong direction, I change them to the correct direction (in the direction of flow, using satellite images and elevation data as sources). Please specify a few highways that you are referring to.