As for the Union Jack: the UK has at least 3 rather different languages (English, Gaelic, Welsh), possibly a few more depending on how you count the different kinds of Gaelic.
Using a country flag to represent a language has always struck me as being silly. Only rarely do they map 1-to-1.
https://www.bbc.com/travel/article/20180206-the-tiny-us-isla...
Also, for what it's worth:
> Some people have characterised Tangier’s way of speaking as ‘Elizabethan’ or ‘Restoration’ English, but that’s nonsense. Languages aren’t static and the Tangier dialect has changed a lot because of its isolation. It’s a distinct creation of its own," Shores said.
[0]https://www.bbc.com/travel/article/20190623-the-us-island-th...
Mixed with, yes, the variant spellings and word choices (e.g. chips/crisps/biscuits) that make it apparent to British English readers when something is American.
EDIT: Of course, it doesn’t matter one bit in the grand scheme of things—feel free to ignore my pedantry over a silly joke :-)