like those used in MS word Equation editor:

superscript and subscript


other mathematical notations

Yes, I keep running into roadblocks in writing SMath versions of common engineering calcs because many, many engineering references use a wide variety of variable formatting not supported by SMath. Just today, I ran into problems replicating a seismic design formula from ASCE 7-22 here in the US, which uses a tilde over different letters and an overline or macron over different letters. Some work in SMath, like Ṽ and a̅, but not W̃ and W̅. I can replace the impossible notation with something SMath can generate, but then I have to explain what it is since it's not the notation in our national design standard here. See example screenshot below.
(In the screenshot, I say that the combining tilde works, but it worked with the letter V, but not other letters.) More options in variable name formatting like what netsonicyxf requested would be really nice, particularly if the intent for SMath is for it to someday be a real competitor with Mathcad.