I came across people from different countries meaning different things when they ask for it. Germans want to get a very milky latte, most of others want espresso with a drop of milk.
If I'm correct Macchiato means "stained", and it can be either espresso with small amout of milk, or other way round, milk with small amout of espresso.
My wild guess Black Macchiato would be Long Black/Americano with a drop of frothy stuff.
^Regarding that black macchiato confusion:
I came across people from different countries meaning different things when they ask for it. Germans want to get a very milky latte, most of others want espresso with a drop of milk.
If I'm correct Macchiato means "stained", and it can be either espresso with small amout of milk, or other way round, milk with small amout of espresso.
My wild guess Black Macchiato would be Long Black/Americano with a drop of frothy stuff.