Here is a latenight kitchen table sketch of the block setup like cedar strip canoe cross section with a cove and bead.
The block concept has a hole in it, 10mm Basalt rebar runs in hole, Mortar in hole.
I dont know if that basalt would flex enough to follow the radius, And if it did, there would probably need be a centering disk to hold it off the side wall of the hole in the block for mortar to set.
The so called pony wall is called a ring wall, or at ground level a ring beam .
I sat up last night and ran Trig calcs on the Planset to get the relaionships of the dome, the equator, the foundation all into cad drawing. Now im puttering around with tape measures, strings, nails looking at what kind of floor space and overhaed space is realistic for living. The wall at equator seems to give the most normal use out of a floor plan. The bulge and return to a smaller radius seems to leave wasted space, but it allows a bit smaller ring beam
Im starting to find that bulge out and back in to the perimeter beam attractive. Similar to the tumblehome on a canoe hull. More labor in the bulge, more materials and cost in a pony wall.
Also finding that i dont want domes to intersect. A modular pod system with arch connections is going to mean no shared ring beam or ring wall, or ponywall. Whatever the configuration would be called.