If you have installed Magefan Auto Language Switcher Extension for Magento 2 and don't know how to test it properly, please follow these simple steps:
1. Enable all Magento 2 caches
All live sites use enabled caches, so make sure that you have enabled all one when testing.
2. Use Developer (Simulate Geolocation)
There is an option in Magento 2 Auto Language Switcher that allows you to test the extension performance.