When I rename a sequence message in an ES diagram the “Invoked Exchange” (which was the basis for creating the corresponding sequence message) will be renamed in the same way. IMO, this “consistent” renaming of the sequence message and functional exchange appears unexpectedly.
Is it possible to have a different name for the sequence message?
One reason for me to try to change the name of a message in sequence diagram was readability. Assume you have a scenario where the same message is sent 5 times from an actor A to an actor B and in a presentation or in a textual description of the scenario you want to highlight or refer to e.g. the third exchange of this message. It seems to be much easier for the audience to find the right instance of message if a certain postfix is appended to the label of the message (e.g. (3)). I thought it could be possible as the “sequence message” object is different from the “functional exchange” object (that is why there is a reference between them: “Invoked Exchange”) but as your answer indicates that does not seem to be the intended way to do such things.