Let me explain in Language, the dominant language of Britain
"Your correspondent's Bahasa (the dominant language of Indonesia) runs out on the first page of a restaurant menu"
You do realize that <<Bahasa>> simply means "a language"? It's like you said "Your correspondent's <<Language>> (the dominant idiom of communication in Britain) runs out..."
The language is simply known as Indonesian, ffs. Yes, Indonesians call it "bahasa Indonesia", but it's the "Indonesia" part that is relevant, just as its "English" in "the English language" that signifies the particular language we are having this conversation in.