The game does not load text from the export.xml file in case of custom localization

When you create a folder with the path /northgard/lands/custom/files.xml, the game accepts only the text.xml file and ignores the export.xml file.
However, I used a third-party program and loaded a custom language into the res.pak file, replacing it with an existing one (for example, export.xml(custom) with export_de.xml), then the language is displayed correctly.
However, the website https://northgard.net/map-editor/how-to-mod/ states that for a custom language/translation, you just need to put the export.xml and texts.xml files in the langs/custom/files folder
Even if you unzip the res.pak file, take an existing language and give it the desired name (export.xml) and drop it into the appropriate langs folder, it will not be displayed in the interface either
Windows 10 operating system