As stated in the subject of this e-mail, the command MathematicaScript
became wolframscript in the newer versions of mathematica. To make
ob-mathematica.el work again with newer versions of mathematica simply
replace all occurences of MathematicaScript with wolframscript in that file.
An extra comment. Wolfram made it's Wolfram Engine freely available
for developers. And I guess it can be used to, for example, produce
Mathematica Plots (or graphics) in the jupyter notebooks using the Wolfram
Language kernel for jupyter
(I am not
sure because I have a licensed Mathematica version and I guess my jupyter
is using that kernel to get the graphics). Would be great to have such
functionality working in org-mode (with-babel). Unfortunately I am not a
developer. But someone else might like the idea too.