Since Tiki 8.x translations for mods should be distributed with the mod itself (instead of placed inside lang/xx/language.php files). The mod should have a lang directory with one directory per language code (following the same structure Tiki uses).
But instead of calling the files language.php they should be called language_modName.php. So for example for the plugin R mod the file should be called language_r.php.
The script get_strings.php can help you to collect strings from your mod source code. But you first need to manually create the language file for each language you want to support (you can create an empty file).
To collect strings from your mod source files to language files run (from a Tiki root dir):
php get_strings.php lang=xx baseDir=pathToModDirOutsideTikiInstallation fileName=languageFileName
If you were doing this for plugin R mod and Catalan language:
php get_strings.php lang=ca baseDir=pathToModDirOutsideTikiInstallation fileName=language_r.php
After running the script, it is important that you rename the array inside language files from $lang to $lang_mod. If you fail to do this, your mod translations will override all other Tiki translations.