When I browse the list of available CTL font families, I find that many of the items don't offer, or don't seem to offer, any CTL language characters (or at least - no Arabic nor Hebrew). It's difficult for me to be 100% sure without bug 151122 being fixed, but - when I choose many of these fonts, what I seem to be seeing is fallbacks being used. I'm guessing the filtering of which font families are relevant for which language families is not reliable enough.