My case officer said yesterday it's the tribunal clarks responsibility
Suffering Christ and his gout-ridden disciples, is there no limit to the shit these people spout whilst on the taxpayer's shilling?
Once Tribunal has made a decision - in this case, that your DC must be statemented - the only responsibility the tribunal clerk has is to send this decision to you and your LA.
If you were contesting the contents of an already-written statement, then the LA must include the changes to the statement that Tribunal has directed in their decision notice. That decision notice is sent out by a clerk, but is written by a judge.
Tribunal clerks aren't trained to write statements. Tribunal clerks don't have the legal authority to write statements. The only people who are responsible for producing the statement are the local authority. As well they fucking know.
And if your case officer genuinely does not know this, then they really, really need to find a new job. Perhaps one where they can be more socially useful, whilst putting their recent co-production training to good use. Tossing off pigs on the farm for money springs to mind.