Can not pre-configure Plasma bottom panel nor Dolphin with Kiosk

Hi list,

This question should probably go to [email protected], but it seems 
there was no activity there since 2019. Also, I already asked on 
discuss.kde.org 
(https://discuss.kde.org/t/can-not-configure-plasma-bottom-panel-nor-dolphin-with-kiosk/329), 
but I got no answers yet.

I am trying to configure some default settings to be able to deploy KDE. 
I am doing my tests with Debian “hopefully-soon-stable” 12 (Plasma 
5.27.2). I follow the kiosk mode documentation, and it works properly 
for some settings (night color, baloo search, power management, Discover).

However, I have very strange results when trying to configure the bottom 
panel:

- From a new user with default settings, I customize the panel (changing 
some applications shortcuts, disabling clipboard)
- Using `fswatch`, I could determine that the relevant configuration 
file is `~/.config/plasma-org.kde.plasma.desktop-appletsrc`
- If I copy this file to `/etc/xdg/`, my settings are not applied to new 
users (while it works for other files like `kscreenlockerrc`)
- As a workaround, if I copy this file to `/etc/skel/.config/`, settings 
are applied to new users BUT the panel gets a height of 30 instead of 44 
(the default).

Also, a somewhat similar issue is for configuring Dolphin (toolbar, left 
panel, right panel, detailed view by default):

- I found that the relevant files is 
`~/.local/share/kxmlgui5/dolphin/dolphinui.rc` (strangely 
`/etc/dolphinrc` does not seem to contain the settings I am interested in)
- If I copy this file to `/etc/xdg/dolphinui.rc`, my settings are not 
applied for new users
- After copying this file to 
`/etc/skel/.local/share/kxmlgui5/dolphin/dolphinui.rc`, settings are 
indeed applied to new users except “overview in right panel” and 
“detailed view by default”

What am I doing wrong? I suppose I missed something from the 
documentation, but could not find what. Any help would be greatly 
appreciated!

Regards,
Yvan