Occasionally I deliberately create a macro with two hot key triggers (e.g. ctrl-1 and ctrl-2 both triggering the same macro). When I sort macros by trigger only the first trigger is listed. The second does not appear in the list and I haven’t found any way of identifying macros with a second trigger (other than by inspecting every macro individually).
Risking not adding anything, but the search field searches triggers by default. I've just put my triggers in the search field to find the bound macros.
You can use the standard characters for modifier keys, e.g.: ⌃, ⌥, ⇧, ⌘. (And, in its brilliantly user-first way, Keyboard Maestro processes triggers typed in the search field. I can type my string trigger for any of those characters in the search field and the macro is executed.)
In case I don't learn "t:" to limit search to triggers. And note that you must not allow a space character after "t:" (or any Search Qualifier I assume) in the search field.