So this man was violent towards you and you left him. Your tribal elders then conferred a title on him as a reconciliatory act. (This in itself is hard to swallow - a man commits violence against a woman of the royal line, and as a result, is honoured.)
He however, rejects the title. Or accepts it but does not want his child to call him by that title. Which one is more accurate?
If he rejects the title, then I can see how that would feel like an affront to the tribe. But really it just shows that the tribe cannot make a 'bad' man good... the reconciliatory act of conferring a title might have worked locally, if the man shared the same cultural background, but if the man is of British culture, then being honoured for committing DV is sure not going to make him grow more respectful. In contrast, it seems to have taught him that he can get away with disrespect and is now taking it a step further by trying to force you into using terms of his choosing. He is exerting control.
If he is happy with the title, but does not want his child to call him by this title, then I can understand his perspective - I would not choose for my child to call me by my title. My name, mummy, mum, mother, the equivalents in our other language, but not my title!
Regarding Cafcass, I do not think they can dictate how your child is to call their father. At most, they can say how you are to refer to him when speaking to your child; e.g. you must not call him 'the bastard' as you would be alienating your child which is wrong.
I think you would be ok if you would refer to your ex as 'your father' when speaking to your child, which is factually correct and in line with British language and culture. Use Papa xxx when talking to members of your tribe, but always 'your father' when adressing your child. It is then up to your child if they want to use a term of endearment such as daddy - you cannot stop them, your ex cannot force them.
I feel for you - your ex is violent towards you, your tribe responds by honouring him, your ex uses this to further exert control over you, a slap in the face this time to both you and your tribe, and the authorities give him right.
And who cares for you in all this? I hope your current partner is a good one.