Karabiner-EventViewer uppercase umlaut not shown

[cova-fe]

macOS version: macOS 14.4.1 (Sonoma)
Karabiner version: Karabiner-Elements 14.13.0
Your Mac hardware: M3 MacBook Pro
Your keyboard hardware: WASD custom keyboard (VID: 1241 PID: 361)

I noticed a minor issue with Event viewer:
While playing around with German characters, I printed umlaut characters (ä,ü, etc..) in the text input test field. Lowercase are printed fine, but uppercase letters are shown as normal uppercase letters, without umlaut.

In Karabiner-Elements uppercase umlaut letter are ok, it happens only in the text input box in Viewer.

I'm not sure wether this is related to EventViewer or some configuration on my mac, but it is a pretty standard one.

Of course nothing critical, but I lost a bit of time figuring out why my rule to mangle umlauts was not working, until I noticed that it was not working only in event viewer :)