Note that the bug I described in the old thread still exists. I thought maybe Trim was just broken but it happens with Split too:
I also tried it in the example file, it’s not just circles but even curves and squares:
Again, recreating the shape from scratch instead of by trimming/splitting/extracting subcurve an existing curve doesn’t generate this bug. Even though Rhino thinks those shapes are identical, as confirmed by running SelDup as shown below: