@Moonlighter
In general if you try to upgrade with a wrong FW region/HW version release, the upgrade process will be terminated with an error message.
Since you current FW is from 2017 and the new one is from 2020, there will be improvements and security patches.
Look for example at the Argentina regional support portal.
You have the option to upgrade to TL-WR940N(US)_V6_200316 or TL-WR940N(EU)_V6_200316.
They have the same new functions and fixes, but for a different region.
You can try one of these two to upgrade to - whichever allows you to.
If you succeed with one of them, the web management interface will be in English and you will lose the current router configuration.
Make some notes (backup/restore won't work) before starting the upgrading process if you decide to give it a go.