Hi René,
We’re really sorry to read you’re facing these kinds of issues with your website.
For many years, the WordPress Customizer is a powerful front end editor that can be used to edit a WordPress website. However, the modifications you made in the customizer shouldn’t intervene with the PHP snippets and the translations. My best guess is that these issues are related to the cache.
Please make sure that you have the latest theme version and that all recommended plugins are up-to-date.
Then, can you clear all activated caching system as well as your browser cache before investigating any further. If you want to read more on what browser cache is and how to clear it, here is an article that might help you: How to Clear Internet Cache in Every Major Browser.
We really think this might solve your issues. In case they still appear, please come back to us.
Thank you. 🙂