Hello sol-vin.
To my knowledge, the language field in the .cfg does not do much. Please make sure that the plugin is set in the correct folder (inside "res://addons/"), as described here: https://cookiebadger.github.io/assetplacer-docs/installation.html
The installation location should match the location specified in the .cfg file. If you are on Linux, note that uppercase and lowercase are treated differently, so if your addons folder is called "Addons", e.g. it might not work.
Let me know if you need further help.