Maybe not strictly a bug, but certainly very unexpected behaviour that most people would consider a bug.
Out of the 24 lowercase Greek letters, only seven can be entered by typing their English name: alpha, beta, theta, pi, rho, tau, phi. I have no idea what’s special about these letters specifically. Sure, not every Greek letter is widely used in math but I (anecdotally) encounter gamma, sigma, omega, or mu much more often than alpha or beta. The only way to get these letters is to Google for it and then copy paste which I think is a significant usability issue.
If there’s no interest in fixing this, I would at least like to know why these specific letters were chosen to be typeable.
It is possible to type most of the rest of them by opening a note line, then putting <name> where is the letter’s name, all lowercase, then copy it (with backslash). I also have a sampler graph of a fair amount of these here: Symbols | Desmos
Also, I didn’t notice this until now- Welcome to the community! I hope you enjoy it here.
While I don’t know the reasoning for all of them, pi, tau, and theta are relevant to polar coordinates and trigonometry, and can be quite handy in Radians or Polar mode. r is also a special variable in this case.
For sigma, if you’re referring to sigma notation for summations, typing “sum” will bring up sigma notation, and “prod” bring up product notation with capital pi.
No, I’m referring to lowercase sigma (σ) which is quite commonly used to represent standard deviation. For example the PDF for the normal distribution is expressed in terms of sigma and mu.