freedesktop - Feb 2024 - Minimal set of icons and what about missing icons

Hello,

I try to dive deeper into your topic. I slightly understand how themes 
and icons are working. But I still miss some aspects.

Do I understand it correct that a theme need to offer a minimal set of 
icons specified here:
https://specifications.freedesktop.org/icon-naming-spec

But most themes do offer much more as this set. But they are not 
consistent.

For example see "system-users". Looking in my Debian 12 with XFCE4 I
see
Adwaita, gnome, HighContrast and Tango do offer that icon. Even them do 
not offer it in all resolutions.

When I use that icon by its name in an application (e.g. Qt-based) but 
the current used Theme do not offer "system-users" what is the
intended
behavior?

The background is I don't want to ship my own application with extra 
icons (except its logo). I want to use the standard logos available on 
all freedesktop systems. But when I found one fitting icon I do discover 
that it is not available on all themes.
So I am stuck.

This "system-users" for example I would like to use it for "Setup
language" (the UI language) menu entry in my main menubar. A
"globe"
would be better but there is no globe in the icons. The internet-browser 
icon do not fit good enough because there is a mouse tick in it in most 
themes.

Kind
Christian