Hi,
HikaShop is not adding the ld-json data in the header of your pages.
If it's added by an extension made by Tassos, then he should be the one fixing it if what is in the ld-json data is incorrect, even if the information comes from HikaShop's data in the database.
HikaShop can't be responsible for what another extension adds to your website, even if it bases itself on the data from HikaShop.
I can't fix the code of his extension for him.
If he has some questions or information for us, like some questions on how to get the user information of a comment when no user account is linked to the comment, I'll be happy to hear them and help if I can. But so far, with the information you provided on the issue, I can only redirect you to him.