Very interesting. I was actually talking with someone about this and they mentioned a friend who was an advocate for the blind. In the US we have an ADA (Americans with Disabilities Act) which dictates that all public facilities (with very few exceptions) have accommodations for the disabled. It is typically geared toward physical barriers to people in wheel chairs, but covers a broad range of things. In any event this person sells and writes software tools that are added to webpages and apps to accommodate the blind. Mostly reading written words and allowing verbal commands. It’s not an ADA requirement as far as I know but just one other thing for developers to possibly enhance apps with.
I guess it would depend on your customer base and the market you are going for as to whether it makes economic sense to implement features. The issue with any company would be a matter of resources and priorities. When having the choice of adding 10 features that 90% of the customers are asking for vs. 2 that only 10% of the customers are asking for, assuming both take the same amount of effort and resources, which ones do you think a company is going to implement?
The question would be how many of my target market, or the entire market over all, only understand Hebrew or Arabic vs. the ones that can understand both Hebrew and English? It may be a large percentage or a small one, that would depend on many factors. Obviously in your case it sounds like you have a lot that fall into the first category.