the keys look pretty simple.
You need openscad and a set of digital calipers, just measure and replicate.
Easier than it sounds :-)

3d printed pla keys will be pretty hard wearing and available in lots of colours.
Can't see any real reason they'd wear out any faster than the original keys.

although 3D printing (unless very high quality) is more likely to be the least long-lasting and lowest quality,
That's just not true.
Depending on the material used they could actually last longer than the original keys.
Unless you're building a muppaphone:
https://www.youtube.com/watch?v=JaL6s4eNNBg

What you actually need to do is find a 3dhubs person near to you.
https://www.3dhubs.com/

Ask them and see if they could produce the stl file as well as print the keys.

But something like that would be pretty straight forward to duplicate in openscad.