2) Share what part is not being translated correctly.
3) How are you creating this part in the default language?
4) Please make a full backup of your site (files and database) and confirm it in your next reply.
If possible please provide access to the staging website, not production.
Please note, that I might need to do some debugging procedures like enable/disable plugins, switch themes, change the default language of the user account, and/or access your website database to debug the issue furtherly.
I will share with you any changes or steps done in this process. Please let me know if you do not agree with the above or if I do not have your permission for any.
I would need to access both your site's wp-admin and FTP account, if possible.
I have enabled the private username and password fields in your next reply.
I suggest you create a new user, set it as an administrator and then add those credentials in the private fields mentioned.
You can safely add your information into these fields.
