The bottom of the grooves also have to be rounded,not just the tops of the lands.
The first picture you posted shows a too-sharp an edge at the bottom of the grooves.
A coned muzzle has from 1" to 2" of coning, a gradual tightening over that distance to the tops of the lands.
This sort of muzzle treatment loads harder with the rounded lands and grooves smoothing that I do - with a lathe and just a finger on the emery or paper, or with the barrel on the gun, rotating my hand and turning the gun 180degrees every 20 seconds or so.
From a machine-cut muzzle crown to a gently smoothed and radiused crown that I use, is usually only a 10 minute job.
The result is a crown that loads easily as the 'shape' of it moves metal & is the shape used for drawing metal.
Before:

After:

The "crown" of this muzzle is less than 1/8" deep, yet allows loading balls .005" under bore size with a .022" patch - easily, using a short starter.
My .69 has a similar crown (almost exactly) & I routinely use a .682" ball in the .690" bore, with a 12 ounce denim patch which I measure at .030" compressed hard. I have also shot it with same ball and a 14 ounce denim that I measure at .034" thick.
This rounded "shape" is the same as used in metal drawing dies.
Look at the filed muzzles of Jaeger rifles - both lands and grooves are filed out enlarging their size, although the muzzles appear to be "square". Closer examination shows they are filed out - they are not coned.

If you are happy with .010" patches - carry on. I'm done here.