SUMMARY
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***
Since upgrade to Kubuntu 20.04 and Kile 2.9.93 selection of other default language for input/spellcheck other than EN not possible notwithstanding the menu. 
All packages downloaded.

STEPS TO REPRODUCE
1. -> Settings -> Configure Kile -> Editor -> Editing -> Spellcheck -> Default language:
2. -> only US/UK/CDN EN to choose
3. thus input of e.g. German ä/ö/ü/ß like years ago again only with \" possible
    but former text with ä/ö/ü/ß are to see.
Also QuickBuild Alt+F1 does not respond.
Also -> Tools -> Encoding some of the codes are not responding.

OBSERVED RESULT
Replaces letters with diacritical signs

EXPECTED RESULT
To be able to use more language packages, input and spellcheck languages and international codes and to be able to refresh the pdf build like I got used to it.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma:        Kubuntu 20.04  
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION