When scheduling a function with macro commands, the game doesn't return an error. It is silently ignored. And because there is no way to pass macro arguments to the scheduled function (see MC-268322), you cannot schedule the function. Just to be clear here, the bug is that it doesn't show an error when you try to schedule the macro function, I'm not asking for any new features.

How to reproduce:

1. Create a macro function in a data pack

   $say WAHHH $(data)
   

2. Run the function without arguments

   /function <id>
   

3. Notice that you get an error: "Failed to instantiate function"
4. Try to schedule the function without arguments

   /schedule function <id> 1s
   

5. Notice that you get no error, but after a second the function did not run.