...knot sure how UCCNC Exact stop works or is coded but, have you tried it?...most of the time high feed rates can give unpredictable results if, not under the control of an error/lag factor.
Linuxcnc uses a G64P.xxx code for Path Blending or a G61 for exact stop
G64 P0.015 (set path following to be within 0.015 of the actual path)
https://linuxcnc.org/docs/html/gcode...html#gcode:g61
Good luck hunting,
DJ