Hello Mr Emura, thanks for your reply and this confirmation.
Unfortunately I cannot use any external data source like files or registry values, since I need to be able to call these command-lines from another software that I use, which can invoke external tools like EmEditor by using command-lines, but not write any files or registry values prior to that (and there are of course other cases where also only self-contained command-lines work, e.g. if I need to send a command-line to my colleague, which they then quickly can use on their computer for some task).
I think that such command-line parameter passing for macros would be a highly useful feature to go with the already super useful possibility to execute macros from the command-line with the “/mf” switch, so I have now created an enhancement suggestion for this, which I hope that the higher powers would at least take into consideration. :-)