For some reason the trim at the bottom of the cylindrical surface is messy - not a clean arc
ShrinkTrimmedSrf then untrim that surface to get a clean edge curve. BTW, ideally, I would not even use the arc directly - DupEdge, and then rebuild the resulting curve to degree 5 and 6 points. The true arc has weighted control points, and EdgeSrf will propagate that into the resulting surface - not the end of the world but the surface may be better behaved if it is ‘non-rational’, i.e. control point weights all 1. I did not do that in my example above but it is not a bad idea. A six point degree five curve gives a very nice approximation of a 90 degree arc.
Shrink, Untrim, DupEdge
Rebuild:
Surface:
Make sure when you MatchSrf at the bottom/trimmed edge, use “Preserve isocurve direction” Match for Tangency and “Preserve other end” at tangency as well, and “Match by closest points” for this bottom edge as well.
-Pascal