Up to now only the old questions are in the App.
To stay useful, the questions database should be updated.
Maybe with an option to switch between the old and the new catalogue (unclear how useful that is).

For now only the top-level topics can be selected for questions. However, in the question catalog the sub-chapters are available as a structure and could be selected for individual learning.

Unfortunately the app isn't available for the newest Android version in Google Play. Unfortunately I do not got a detailed error message. I would like to try out this app on my phone. Let me know if you need some testing.

Hallo Dominik,
was hältst Du von einer Erweiterung, so dass man den Status und den Stand der bearbeiteten Fragen sichern kann und auch auf anderen Geräten wieder einspielen kann?
Beispiel: Fragen auf Smartphone unterwegs bearbeiten und zu Hause den Stand auf das Tablet zum Weiterarbeiten einspielen.
Gruß
Volker

Rendering is implemented sub-optimal for now. Although the graphics for the new question catalog are available as SVG graphics this would technically be possible but requires an overhaul of the question display screen and is a bigger undertaking. Therefore, this Issue to keep this in the loop for future development.

Fehlendes Bild bei Frage: "Welche Gesamtkapazität hat die folgende Schaltung? Gegeben: C1=0.02uF; C2=10nF; C3=10000pF"

Had to pick the app from fdroid to find the link to the repository and forgot which question had the missing space while doing so ^^

Would be nice to have a "fix typo" option in the 3dots menu of the training mode

https://gitlab.com/fdroid/rfp/issues/592

Was fehlt, ist noch die Zustimmung des Apperstellers, @meyerd

Ist es in Ordnung, die App in F-Droid einzubauen?

You can add Screenshots for F-Droid, too, if you want.

https://f-droid.org/en/docs/All_About_Descriptions_Graphics_and_Screenshots/

https://gitlab.com/snippets/1895688

The description on F-Droid uses the term "ham radio" instead of the proper name "amateur radio".

This makes it hard to find the app as it does not show up when searching for "amateur radio", this should be fixed.

For learning implement a list or overview of wrongly answered questions to especially go over those again.

It needs a way to export the progress and re-import it.
That feature would be useful when when a hard reset, it would avoid loosing all progress.
It could also be useful when a phone change is needed, it would avoid loosing all progress.
Also it would be useful to backup general progress for other scenarios. (phone lost or stolen, etc.)