There's one inconvenience with country names with non ASCII-7 characters: country drop-down lists. They are so long you almost always start typing the name first. If you are looking for, say, a hotel in Turkey (now Turkiye) you don't necessarily have the keyboard layout to readily type ü.
In fact country lists are probably one of the most annoying unsolved problems in UI to date. Especially where you are asked for your phone number and the country code is a drop-down. Seriously, how is finding an item in a 200+ list easier than typing 1-3 digits? And especially if the web site is in a foreign language and you don't even know what your country is called in that language? (Been in this situation in France once, had to urgently sign up on a web site with my UK phone number that I had at the time, ended up googling what the UK is called in French just because the web site required my phone number!)
In fact country lists are probably one of the most annoying unsolved problems in UI to date. Especially where you are asked for your phone number and the country code is a drop-down. Seriously, how is finding an item in a 200+ list easier than typing 1-3 digits? And especially if the web site is in a foreign language and you don't even know what your country is called in that language? (Been in this situation in France once, had to urgently sign up on a web site with my UK phone number that I had at the time, ended up googling what the UK is called in French just because the web site required my phone number!)