Success!
Just tested modifying gcode manually to make radiused slots. Meshcam was an failure, even with pocketing it. G18 changes to XZ plane then plunge to first point and use g2/g3 command for end point. Can set the radius in the G2/G3. Will work for fan frets also but involves analyzing the radius of each fret. Just select radiused fret, may have to simplify curve first, and use “Radius” command. Getting the exact start points also a bit of work. Maybe, adding points to end sections of fret, then use “What” command to grab the coordinates. Also setting a cplane to your origin point to input into gcode. Unfortunately Easel Pro doesn’t support G2 ARC commands. Tested in Camotics and ran smoothly. Hopefully my machine supports it. Easel pro so nice though wish it had that support.

%
(FILENAME: Fret Slotting Toolpath G18 XZ Arcs.nc)
(STOCK/BLOCK, 100.000, 500.000, 6.350, 50.000, 250.000, 6.350)
(TOOL/MILL,0.6000,3.00000,38.000,0.0)
G00 X0.0000 Y0.0000 Z2.0000 (fast travel to z height of first point)
(Zero Fret)
G00 X-26.5000 Y230.9687 Z2.0000 (START POINT fast travel to xyz of first point )
G01 F120.0 Z-2.1667  (linear movement plunge rate down to z point)
G18 F600 (select XZ plane sets feedrate for cuts)
G03 X26.5000 Y250.9687 Z-2.1667 R586.8924 (END POINT Counter clockwise arc from XYZ, with Radius of fret)
G01 F120.0 X26.5000 Y250.9687 Z-2.4167 (linear movement plunge rate down to next XYZ)

G18 F600 (select XZ plane sets feedrate for cuts)
G02 X-26.5000 Y230.9687 Z-2.4167 R586.8924 (Clockwise arc from XYZ, with Radius of fret)
G01 F120.0 X-26.5000 Y230.9687 Z-2.6667 (linear movement plunge rate down to next XYZ)

(Rinse and repeat lowering z in incrementally stepdown)
G18 F600
G03 X26.5000 Y250.9687 Z-2.6667 R586.8924
G01 F120.0 X26.5000 Y250.9687 Z-2.9167
G18 F600
G02 X-26.5000 Y230.9687 Z-2.9167 R586.8924
G01 F120.0 X-26.5000 Y230.9687 Z-3.1667
G18 F600
G03 X26.5000 Y250.9687 Z-3.1667 R586.8924
G01 F120.0 X26.5000 Y250.9687 Z-3.4167
G18 F600
G02 X-26.5000 Y230.9687 Z-3.4167 R586.8924
G01 F120.0 X-26.5000 Y230.9687 Z-3.6667
G18 F600
G03 X26.5000 Y250.9687 Z-3.6667 R586.8924
G00 Z2.0000

(END)
(OF PROGRAM)