> The bigger conondrum might be which flag to choose for Arabic.
By your logic I'm not sure why this is a conundrum—Saudi Arabia, of course!
Arabic is actually the perfect example of why flags for languages are problematic—just because two countries share a language doesn't mean they're on good terms with each other. That's easy to see with Arabic because tensions in the Middle East are always in the news. You know instinctively that using the Saudi flag to represent Arabic would be a terrible idea.
But the same problems apply to other countries, just less prominently. African people often have... complicated feelings towards the countries that were their former colonizers. The language is theirs now, for better or worse, but that doesn't mean that they're comfortable picking a French flag when selecting the language for their personal device.