Can anyone explain in more detail about this issue with the clone?

I've encountered this issue several times myself. I even argued with Amber and, I think, with Kael about this clone thing; they told me to read the FizMig guide, but in reality, the clone disappeared much earlier than it should have. I think this depends on whether or not the unit has the Water skill, but I can't say for sure.

Added 5 minutes later

I hoped that the training would appear naturally at some point. And in general, I didn't scout the map to see how to complete it with Arham on cheats. So I was hoping to get some kind of air jump, flight, or city gate. Therefore, just in case, I took the Air skill. And I checked the magic in the fortresses during the playthrough, each time I captured a fortress, using cheats, of course, after making a clean save for scouting.

Well, maybe someone else did the same (I mean, used cheats), although they could have just run through it. And regarding the magic: were you too lazy to go into the editor, or did you again use "infinite running" to find out that there's nothing good to be found? Why did you check this during the playthrough, and weren't you afraid of wasting time on it?