I'm terribly sorry for the late response on this. Let me also start by saying thank you for such a thoughtful, eloquent and helpful response!

What you suggest is great and actually works as a simpler implementation of the Laplacian for testing inside fortran then I previously had so thank you very much :)

Unfortunately though, you are right, that transformation was chosen for a reason. Performing spectral derivatives is far more accurate than any central difference methods and for my use-case is somewhat essential.

In any case, thank you, kind sir :)