Do you want to single-point engrave along the "centerline" of the 2 lines representing each side of the text?
Maybe get some midpoints & draw splines thru them?
Or do you want to engrave along the lines themselves?
You might want to fit a spline thru points on the lines (endpoints or ?) & tweak from there.
Production: NX10.0.3.5 MP5 + patch/TC11.2
I'd rather be e-steemed than e-diseaseled
You can cut the curves from the dxf, but as you saw it will be choppy, but that's what your customer provided. I would explain to the customer that this is like providing artwork to a printer - you will cut what they provide.
I'm sure you can clean this up the curves in CAD - not my expertise.
Once you have the curves, the question is - are you cutting the outside, inside, or on the curves. If it's the outside or inside, extrude the curves as a solid, and cut like anything else. If it's on the curves, use curve/point drive method in surface contouring - select a loop, new set, select the next loop.