I did some digging and we get Hawaii-Aleutian Standard Time instead of GMT-10 here because of this fallback to the long tz name:

babel/babel/dates.py

Lines 659 to 662 in 2b93a4a

	if width == 'short' and name == NO_INHERITANCE_MARKER:
	# If the short form is marked no-inheritance,
	# try to fall back to the long name instead.
	name = metazone_info.get('long', {}).get(zone_variant)

When I get rid of it, get_timezone_gmt is used instead.

Originally posted by @tomasr8 in #1194 (comment)

We should figure out what the correct formatting is, and then start doing it.