sr_CS locale seems useless/outdated should be changed to sr_RS and sr_ME

https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2#Officially_assigned_code_elements says about CS:

Originally Czechoslovakia, later Serbia and Montenegro

Code taken from name in Serbian: Srbija i Crna Gora

Now divided into Montenegro (ME) and Serbia (RS)

CS previously represented Czechoslovakia (ccTLD .cs was never assigned to Serbia and Montenegro; .yu was the ccTLD of Serbia and Montenegro, as name was changed from Yugoslavia). Czechia uses (CZ) and Slovakia (SK)

glibc does not have such a locale either:

$ locale -a | grep  ^sr
sr_ME
sr_ME.utf8
sr_RS
sr_RS.utf8
sr_RS.utf8@latin
sr_RS@latin
$

On systems where there is no sr_CS locale, the compose file

https://gitlab.freedesktop.org/xorg/lib/libx11/blob/master/nls/sr_CS.UTF-8/Compose.pre

cannot be used because one cannot set such a locale.

Probably there are no systems which have a sr_CS locale.

If that compose file is useful for Serbian, it should probably be moved (or at least copied or linked) to sr_RS.UTF-8/Compose. And sr_ME.UTF-8/Compose should then be created as well containing a line

include "/usr/share/X11/locale/en_US.UTF-8/Compose"