Right now, if I define a macro at the template or global level, I have no simple way of knowing that this macro exists at the host level

What would be great is showing the macros and values inherited in the macro definition page, with

• a link to the macro definition at the template level
• a way of changing the value (maybe a grayed out value that can be changed and turns to black or whatever)
• a reset to get back to the default value.

Idealy the same thing should be done at the template level when having a hierarchy of templates.