I have found that Pakistan country name is translated into many languages, including ku-Arab. Its capital, Islamabad is also translated to many languages, including ku-arab.
As you can see, the only difference is the letter a. I modified the key for Islamabad, according to name:ku-Arab | Keys | OpenStreetMap Taginfo. But now, I question myself about the capitalization of the keys. What is the rule for this?
Regarding the capitalization of multilingual name keys, there’s a simple rule following the relevant ISO standards - the language is given in two or three minor letters according to ISO 639. The script type (like Arab, Latn, Hant) uses the four letter ISO 15924 code, starting with a capital letter and separated from the language with a dash ‘-’.
Unfortunately, there are a couple of old keys that don’t (yet) follow this rule. For example ‘name:ja_kana’ These should be listed in the Wiki Multilingual names - OpenStreetMap Wiki .
A possible case of confusion: While languages are tagged in minor letters, country codes use capital letters. E.g. name:fr (the name in French), but school:FR (the type of school according to a scheme used in France). Country codes are those defined in ISO 3166-1 alpha-2.