I have been thinking about the following question quite a bit recently: why do other languages, which often do not even use the Latin alphabet, seemingly get to decide on the way their words get Latinized in English, even if the original pronunciation of the letters chosen for their Latinization does not match the pronunciation of those words.
As an example of the mess this gives, let's take the word "chi", which is the Latinization of the name of a greek letter. However, because a 'ch' is usually pronounced like 'tsh', the greek letter would more accurately be represented by "ki", or "khi" for that matter if you want to emphasize the aspiration.
While that one's pretty 'tame', so to speak, it sets me up to talk about the Chinese word "qi", which is pronounced like 'che' (or 'tshe'). The martial art Tai Chi has the exact same pronunciation as 'qi' (or at least, for all intents and purposes, they are indistinguishable in the English language), but that one uses the 'ch' instead, making it even more inconsistent.
Another example is the name of the current president of China, "Xi". His name is pronounced like 'Zhe', so why is the letter X used there? I understand that this resembles the pronunciation of the first letter in "Xavier", but while Xavier simply has a silent 'k' sound at the start (similar to how the k is silent in words starting with 'kn'), the Chinese name "Xi" doesn't have a silent k at all. It's just a 'zh' sound at the start.
Another example is Arabic words with a Q not being used in the same way older English words (loanwords from Latin, mostly) are pronounced. In all of those cases, the q is always followed by a 'u', forming 'kw' when used together. In Arabic words like the countries of "Qatar" and "Iraq", they simply use the q to indicate a 'k'-like sound.
To get to my question: why do other countries, where the Latin alphabet is not used, get to decide how their words are transcribed into English, using the Latin alphabet, even if the letters they choose for their transcriptions do not match the pronunciation typically associated with those letters? If the country of origin gets to decide, what's stopping them from transcribing the word pronounced like 'tshi' into 'po', and claiming that the 'p' is pronounced 'tsh', and the 'o' is pronounced like 'e'?
I understand that English pronunciation and spelling are barely connected at all even when it comes to words that have been in the language for a long time, but as far as I know, that's mostly due to historical reasons, not due to some arbitrary choice of transcription that doesn't have to be this complicated, but seems to just be rather randomly picked.