I am using Typo3 version 9.5.13 with 16 languages, there is a language 'Macedonian(mk)' and I have added a translation for this language with a key in Typo3 template setup, but it's not taking this translation and shows the default translation. This language is not in the Typo3 Supported languages list.
Thank you
In order for TYPO3 to support "mk" locale (and thus, XLF-based label files with "mk.locallang.xlf") one needs to add this line to typo3conf/AdditionalConfiguration.php
$GLOBALS['TYPO3_CONF_VARS']['SYS']['localization']['locales']['user']['mk'] = 'Macedonian';
This is the beginning to make it even possible to allow mk for TYPO3 Backend and Frontend - related to label files (XLF).
The other parts (creating a sys_language record, adding an icon, adding "mk" to the site language etc) are still valid and need to be done as well, in order to determine "mk" in a multi-language setup for TYPO3 Frontend.