Hello, I'm Greg, here to help you with this.
There is an edited font file for adding the Jawi alphabet at the respected programmer site here, which has a lengthy explanationa and contact link for the author: https://github.com/jawi-mnh48/jawifont
More on how to add Arabic to keyboard here:
https://www.youtube.com/watch?v=w2x7GO9nxLQ
If you want to express your opinion on this you may be able to help Microsoft improve this product/feature by using the Feedback Hub in Start Menu. While they will not see it here, Microsoft developers DO read feedback from customers that comes in via the Feedback Hub, so that is a great way to share your thoughts on how to better serve you as a customer.
I hope it helps.