Macros are deliberately very simple - they provide a single list of commands, and that’s it. Macros are not able to handle “conditional” commands. You can’t tell a Macro: “IF it’s an MP3, THEN export as MP3, ELSE IF it’s a WAV, THEN export as WAV…”
If you need to use conditional commands, you need to use a more powerful scripting language than a normal Macro. Audacity provides two such options, but both are significantly more complex (and more powerful) than Macros. The options are:
- Nyquist Macros: https://manual.audacityteam.org/man/nyquist_macros.html (additional information here: https://wiki.audacityteam.org/wiki/Nyquist_Macro_Tutorial)
- Python Scripting: https://manual.audacityteam.org/man/scripting.html