FindAll

Is there a way to integrate this with macro searches to be able to find all instances of a keyword across all macros on your character(s) as well?

Something like:
//findall Idris
Finds Idris across all characters
Finds all macros/equiset #s that have "Idris" term or Idris in the equipset (across all characters or main)

Sometimes a new item replaces a lot of older ones (Nyame set) and it would be nice to run a keyword search and find all places that item is used on your character so that I can update all macros at once.

I dont think so. This is where the power of gearswap starts to shine - you can do a find and replace in notepad plus of your .lua. The in game equipsets are so clunkly.