Just a update. I tried the Leather Master "Soft Finish" on a part of the wheel. It was "dry" to touch, but not semi stuff like oem, and it didn't look oem. It also came off quite easily, so it seems it never really adhered well to the leather.
I can definitely tell that the top coat is worn away, both by looking and by feeling, and also noting color transfer when cleaning.
At this point, I'll just live with it until I can afford a new (or lightly used" oem wheel). Really blows that the top coat can wear away like that...