Hi,
I don't get the error on the jf_content table. I tried many things but never got that error. For example:
i.imgur.com/N7pCNjZ.png
So either you could follow what I wrote in my first message and provide the full error message:
Could you activate the "debug" setting of the joomla configuration and try again ? It should display an error message with more information on where the problem comes from which will allow us to tell you what to do.
Or you could provide precise instructions on how to reproduce the error so that I could activate the debug and check the full error message on your website myself.
Regarding the error "The translation override file /language/overrides/en-GB.override.ini is invalid. Please use the 'Debug languages' option of the Joomla configuration to understand what is wrong with it before adding new translations.", I do get that message. I actually had that message before when I first arrived on your website. I followed the instructions of the message and edited the language override file under the Languages tab of the HikaShop configuration. There, I could see an invalid line:
i.imgur.com/94gwGxt.png
If I remove that invalid line, then I can translate text again on your website and everything works fine.
The problem is that I don't know how you are able to get that wrong line added to the language file.
Could you provide precise instructions on how you added that "<p>salted-herring</p>" text ?
So basically, you're saying that not much works, but you gave two errors which I'm not able to reproduce on your website so we can't move forward like that. I'll need more information from you to be able to understand what's going on.