The present design looks positive, a bit more of range now and possibly progressive enough. I am not so convinced about that locking in effect at zero position you wrote , at 12 degrees and a bigger radius snapping in there. I can imagine this could induce some chain vibration when overrunning this zero spot in certain conditions so I would not want to introduce this feature. But what do I know, just saying. Anyway, BMW or Kawasaki did not include this locking shape in the zero position and they had their ESAs for more than half a century with no troubles from them, only a smooth ending of overrun from either side on the ramps instead plus spring load and steep gradients.
Did you have some welding on one component while finding new shapes, in the photos it shows some rough edges like weld ?
When all is finished and case hardened I´d think no hard milling is required here, heat treatment deformation should stay negligible for the purpose.
Many years ago I had some Belleville washers for inspiration to avoid all those tiny springs. But later I came to keep them with my new design of ESA and am very positive to get no troubles , no spring blockages expected, so no breakages. But then I cannot tell much about your tests with Bellevilles , look pretty hard to me. Also I don´t know if there may be a limit of cycles with these, only had them in plastic injection moulding business - with numbers of broken washers too.
Vic