1. In not a programmer, but affected user, this is one of issues preventing me to move to Linux.

2. In Plasma keyboard and mouse shortcuts does not work in multiple layouts.

For example:
a) I cannot set CTRL-W to my mouse button to close a tab, in Russian it does not work, since it is CTRL-Ц in Russian and KDE binds not to physical buttons, but to a layout.

b) Set CTRL-Shift-> (the key right to left hand Shift) to open some app (I use it for calculator). It will work with English, Estonian, but not Russian layout (in Russian it is CTRL-Shift-| ).

Bugs in KDE's Bugzilla:
https://bugs.kde.org/show_bug.cgi?id=453661
global shirtcut

https://bugs.kde.org/show_bug.cgi?id=480490
shortcuts in app

https://bugs.kde.org/show_bug.cgi?id=462274

As I understood from those discussions, it is a QT issue:
https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/issues/416
and
https://github.com/xkbcommon/libxkbcommon/pull/523