Thank you for the response.
Meanwhile I have created simple ‘static HTTP’ workaround to edit that table, so I’m not blocked with this issue now, but your plugin is more functional than my solution so it would be great to have it working sooner or later.
Please let me know if you need some additional diagnostic data.
Just to add, I’m on WP 5.4.1, your plugin is not marked as tested with this version yet.