If you were to make a mapped key.

You would give it a hotkey.
Then click the 1, below steps in the bottom left pane.
In the right pane there are actions.

Right click and go Keystroke Actions > Warcraft Macro Action.

That takes you to a screen where you can make macros.
You need to assign a unique keybind for the macro.
I don't use IS Boxer macros much, but have used the same keybinding as my hotkey before.

The macro window doesn't suffer the 255 character limitation that wow macros do.
And you can check the boxes to return to previous target.
Or to assist the active character first, etc.
You can also use {FTL} as an argument, /target {FTL} will target the character whose window the key press originated in.

Once you're done, export.

You will have whatever macro on the keybind you chose.
You won't have a warcraft macro, nor an icon or a cooldown timer on the macro button, etc.
But you can copy/paste your macros much easier.
And you could logically place them into keymaps, and drag that keymap with the macros already made onto a new team.