> but I am wondering how much time and effort has gone into that
For me, it was the best part of 4 months of mornings, evenings and weekends - and roughly 40% of my sanity (quaternions took the other 60% a few years ago). And the work is nowhere near finished. Knowing that I still need to find a proper fix for CJK punctuation brings me out in hives. I've also developed a special hatred of Thai fonts.
As for styling a single Arabic glyph within a word ... has anyone in the world managed to do that? It's when I failed to achieve that idea I decided to throw in the towel and release the work as Good Enough because I've Had Enough!
Still - it was an adventure[1].