can not build current German Language pack

[si6ned]

Probably similar issue than #3981, so I can elaborate. Can you tell me what's wrong?

Steps to reproduce

1. Update fork from main branch
2. run: gradle addons:languages:german:apk:build
3. get lint errors

Expected behaviour

with older version I could build a Language pack with custom keyboard layouts.

Actual behaviour

Build fails:
Complains that C/C++ Platform version 15 is unsupported by this NDK, using 16 instead.
Lint errors (Missing MainActivity, ....)

Versions:
Android Studio Iguana
JDK 34
NDK 23
Java 17

Android OS version:
10?

Device manufacturer and model:
na

List of installed add-ons (like languages, or themes):
Gradle, Flutter, Dart