Most KDE applications won't accept accented characters, showing instead ���. This happens in Kate, Konsole and Dolphin (although not in Konqueror; nor in Chrome, LibreOffice, etc).
The fonts support accented characters as I can past a test sample (such as "áááÀ���") and is shown correctly.
> locale LANG=pt_PT.UTF-8 LANGUAGE=en_US LC_CTYPE=pt_PT.utf8 LC_NUMERIC=pt_PT.utf8 LC_TIME=pt_PT.utf8 LC_COLLATE=pt_PT.utf8 LC_MONETARY=pt_PT.utf8 LC_MESSAGES=en_US.UTF-8 LC_PAPER=pt_PT.utf8 LC_NAME=pt_PT.utf8 LC_ADDRESS=pt_PT.utf8 LC_TELEPHONE=pt_PT.utf8 LC_MEASUREMENT=pt_PT.utf8 LC_IDENTIFICATION=pt_PT.utf8 LC_ALL=
EDIT (after replies) :
I'm using Debian 9.4 (Stretch) with KDE Framework v.5.28.
- kde-l10n-pt package is installed
- System Settings > Regional Settings > Language is set to "American English" (I prefer to see messages and dialogues in English)
I added a few locale's while trying to fix this issue:
>locale -a C C.UTF-8 en_US en_US.iso88591 en_US.iso885915 en_US.utf8 portuguese POSIX pt_PT pt_PT@euro pt_PT.iso88591 pt_PT.iso885915@euro pt_PT.utf8
dpkg-reconfigure locales I set the language to "en_US.UTF-8 ".