When you right click the Mixer track it will show the RealTrack or RealDrum name in the generate menu so I don't know how you would change that depending on where the cursor is and if it would generate just that instrument section, and if you drag render what name will it then use ?

That's why I showed the instrument change in the Tracks view as you can see visually exactly what is where as you have partial regen that will generate any section of any instrument change on the same track, you can see what is coming and what has been:

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