Is there a way to see every SmartApp (both custom and built-in) that has a certain mode flagged in it? I assume not. I can’t find it in the IDE (which is where I would think it would be).
Basically, I have a “Home” mode and I want to add a “Working from Home” mode. They will be similar, so I want to find all the one’s with Home flagged in them and see if I want to add Working from Home.
I sort of found it under My Locations…Smartapps (for the location). But I have to go through each one to see what the settings are. No way to filter by mode.
FEATURE REQUEST! 
It’s difficult to implement because “location.mode” can be referenced anywhere in SmartApp code… No declaration is required in Preferences.
I actually think this is a non-trivial security hole, because a common use-case for Mode is “Home/Away” linked to alarms and maybe even locks.