what an interesting conversation this is As I’m from the United Kingdom. I feel I can elaborate a little bit more on what @sonmachinima has said.
Before I go any further I would just like to say I am not trying to deride Americans in any way. I am merely trying to give a bit of extra context, with regard to the differences between American and great British English
When a certain historical event occurred. (I’m sure I don’t need to go into the finer points of American and British history on here) The US started to develop its own way of speaking and writing using great British English or original English as a base But over time they moved away from traditional English phrasing and spelling. So in essence, American or US English as it’s referred to today is around 300 years old.
In contrast original English, or great British English as it’s referred to today is far older and therefore more complicated. It has its origins in the fifth century A.D., meaning it can probably be considered an ancient language as it over a millennia and a half old. Many languages in Asia, such as the languages used on these shows, just like great British English are also very old. So it wouldn’t surprise me if in great British English we have words and phrases which aren’t considered to be part of American English that more accurately describe what is being said in many of these dramas. So in some cases it might be better that British English is used for subtitling. However, the downside to that is that some of our friends across the pond may not fully understand what is being said . Due to their divergence from great British English.
As a Britain I will be the 1st to admit that we British have something of a superiority complex when it comes to be English-language 
but there are reasons for that, some of which I have probably explained above. When Europeans learn English, they tend to learn great British English, where as in Asia, a lot of people tend to learn American English, which from the British point of view is unfortunate, but on the other side of that argument. American English is probably easier to learn, thereby making it easier to break down language barriers.
all of this being said, there are aspects of English that we British find confusing as well due to the age of the overall language, but we are perhaps a bit more aware of the history surrounding the language, which means when we see or hear something unusual. We will immediately think to ourselves ‘that must be a word or phrase which isn’t often used any more, so I will have to look that up’ so usually we will only be confused once,. But if you’re confused by the English-language please don’t be disheartened because the reality is the English-language confuses us all from time to time, even in the place of its origin