I see some questions like compose key - Some entries in ~/.XCompose are ignored. How can I fix that?, but they are from nearly a decade ago, and are about the personalized file, not the system one.
I'm finding that some of the characters in the system file, /usr/share/X11/locale/en_US.UTF-8/Compose, work, and some don't.
For instance, typing multi C C C P produces ☭ (in vim, or chrome browser, etc.),
whereas typing multi L L A P produces <beep>AP rather than the Vulcan hand sign, which I just now entered as <ctrl><shift>U 1f596.
This is on up-to-date 20.04 Ubuntu.
I have a similar problem with my .XCompose file, where my compose sequence for U1F37A works, but the one for U26BD ⚽️ doesn't.
I include this example only to demonstrate that it isn't because its a 5-digit Unicode value; I want to restrict this question to the system file.
