Your code will work only if you have the "{product}" TAG but in your case you don't have it, for testing purpose can you unpublish the "HikaShop product tag translation plugin" and test it again to see if your have the "{product}" TAG ? if that's the case, the issue is coming from your "HikaShop product tag translation plugin" if not, one of your plugin is "hiding" that TAG.
Your code will search if you have a "{product}" tag on you product page, and then replace it (and delete the <!-- -->), but if it don't find any tag it won't replace anything.