geo_2025Jun4a.gh (52.5 KB)
As noted yesterday, R8 works and R7 fails. Appears that R8 is more robust about invalid offsets.
P.S. The yellow group in this R7 version removes self-intersecting offset curves. It works in R8 but does nothing because there are no self-intersecting offset curves in R8. There are other differences that (presumably) could be cleaned up as well.
geo_2025Jun4a_R7.gh (55.3 KB) (DEPRECATED)
P.P.S. This version using Clipper2 appears to be the ultimate for R7. Unfortunately, it fails in R8 because it generates six self-intersecting offset curves (in R8). 
But looks great in R7, and SrfSplit is ~15 times faster in R7 
geo_2025Jun4b_R7_Clipper2.gh (52.1 KB)