Thank you for using Apple Support Communities. We understand that your text message notifications appear in a different language on your Lock screen. This is not expected behavior and we're certainly happy to help you.
If you haven't already, we recommend restarting your iPhone and the Messages app. The following Apple Support articles will help you with these next steps:
How to force an app to close on your iPhone, iPad, or iPod touch
Restart your iPhone, iPad, or iPod touch
If the issue persists, reinstall your iPhone iOS with iTunes. This step can resolve possible software issues. When reinstalling iOS, iTunes will completely remove your current software and install a fresh version. While iTunes will try to do this without removing data, it's a good idea to make sure you have a recent backup before trying this step.
How to back up your iPhone, iPad, and iPod touch
Use the steps in the link below to reinstall iOS with iTunes. Be sure to choose the "Update" option for this step:
If you can't update or restore your iPhone, iPad, or iPod touch
We hope this information helps you reach a solution.
Cheers!