anyway, in a next beta you can set this in texmf.cnf.lua:

return {
   content = {
       directives = {
           ["fonts.usesystemfonts"] = false,
       },
   },
}

Best do that in texmf-local as a next update will overwrite the main cnf file. Entries in the he local file overload main ones.

(1) Where resides above mentioned "main cnf file"? Useful as template for local changes.

(2) I presume that the main cnf file is read in first and the local one after that. Thus changing only that what is done in the local file. Correct?

Hans van der Meer