Lathe Macros

Maybe the lathe is not touched-off correctly for diameter?

Where was the tool tip when you started?

(for the radius macro it should be possible to make a very good guess of the starting position, but the macro as it stands doesn't try)

5 m/min is a pretty low surface speed (the macros run in CSS mode)

I was upbraided earlier by a friend from the Motor Club about this, as he watched your video and thought that I should have defaulted to a 55 degree angle as anything other than Whitworth is an abomination.

Adding the compound angle wouldn't be too hard, but I doubt that cutting buttress threads is that common, and you can always MDI the G76 directly if you need to.
I think that 29.5 is "not terrible" for Whitworth, but I would need to sketch a diagram to be sure. It's probably not ideal for BA threads (47.5 degree) or Panzergewinde (80 degree)

I also suspect that the macro takes many more passes than strictly necessary,