In my experience a lot of this is quite incomplete. Obviously this uses a dataset like "official languages" of each country.
For example, English would grt you very far in the Netherlands, but its not colored. Dutch can get you quite far in South Africa, but its not colored. English in particular should color most of the globe, except countries like Russia, France, and a few other blatant exceptions.
Agree and think the use of data on what languages are spoken and by how many people would help. This app would be vastly improved by the incorporation of more data in general. At least language differences in the administrative divisions of countries should be reflected. Entering Punjabi gets you all of India, which I am doubtful of. I wanted to see if Malayalam does as well, but it is not in the list. Entering French also gets you all of Canada rather than just Quebec and maybe pockets in New Brunswick and Manitoba. Cantonese is not in the list. It is good though and I don't mean to knock it, only to suggest how it could be extended.
Or just color coded from white to 100% of that color based on the number of speakers in that country. A language being one of the official languages of the country doesn't guarantee that it will be useful in traveling that country, only that it will be useful when interacting with the government.
Can confirm, here it'll be problematic for one to speak in English with anyone younger than 16 / older than 40 and/or outside major population centers. (though in my experience, its the same situation with English in Austria and Russian in Latvia/Lithuania).
Been to Russia a few times the last 2 years, for a total of a few months, and my English was useless. My German was decidedly more useful, even if just to understand Rucksack, Butterbrot and Schlagbaum.
For example, English would grt you very far in the Netherlands, but its not colored. Dutch can get you quite far in South Africa, but its not colored. English in particular should color most of the globe, except countries like Russia, France, and a few other blatant exceptions.