Here's a method that works for creating a "real" shortcut to a metro app:
Go to Control Panel\All Control Panel Items\Default Programs\Set Associations
Scroll to the bottom under "protocols" and note that the description column next to each of the metro app shows URL:something.FARR and Windows apps
Create a shortcut somewhere FARR can index to "something://" (excluding quotes).FARR and Windows apps
Rename the shortcut (it'll be called "New Internet Shortcut" by default.)
For example, windows 10 calculator shows URL:calculator. I create a new shortcut on my desktop pointing to calculator:// and titled "Calculator App"
The Calculator icon is used with my title, and the shortcut is found and launched successfully from FARR.FARR and Windows apps
Kind of a farr cry from the index-free ease of normal farr use but if there's a metro app you use frequently it might be worth it.
I got this idea from this link
that I found here