Hello
Are you able to communicate in English?
I can help you to update your htaccess file and rewrite rules. I have over 21 years of extensive experience with Apache and its modules, including the mod_rewrite module and have completed many projects with issues similar to yours, over many years.
If you would like to send through a copy of your htaccess file the way it is now and a detailed description of what exactly is happening regarding updating the Wordpress site and the errors you are receiving, as well as what version of Apache you are running, we can confirm and I can complete the project for you.
I can also clean up and optimise the code where required to ensure your site runs as a high performance server, with specific custom developed directives that can speed up your site performance up to 30% faster on some requests.
Thank you
Darren