I get that error, too.

What I've done now is unpublish the page, delete the translation (the
full page), and copy plugins from English again.

So, it's all prepared for you to work on, but any previous changes are
lost :-(

Please make sure to remove the social media pictures before you add any
title texts to them.

Additionally, can you please make a bug report for inkscape-web at
https://gitlab.com/inkscape/inkscape-web/issues ?

Kind Regards,
 Maren