The thing is, we're generally playing the game in English (well, Swedish with a sprinkling of English in my case, but the principle is the same), not Taladan or Galifarian or whatever passes for Common in the setting in question. So even if the food's name is "Bokippa" or whatever in Taladan, that gets translated to "Sandwich" at the table.Call 'em sandwiches. Who cares if there's no Earl of Sandwich to name them?
It reminds me of a Tolkien thing. Apparently, the names "Merry" and "Meriadoc" are not the hobbit's "actual" name. His name is actually Kalimac Brandagamba, which leads to the nickname "Kali", which translates to "handsome" or "happy". So when translated to non-English languages, it properly should be changed to something similar in that language (although looking at his name in different languages, most haven't – I wonder if that might be because translators didn't want to get him confused with the Disney dwarf).
While Tolkien didn't particularly care for culinary history, he did care about linguistics. One of the earliest translations of LOTR was the Swedish one, by Åke Ohlmarks. Ohlmarks came from a tradition of translators that were more interested in interpreting the original text, not necessarily translating it directly, and as such he took some liberties by embellishing the text, and also got some things wrong (for example, there's some confusion about Eowyn's and Merry's fight against the Witch-King, where a "she" is translated as "he" or vice versa, and there are some occasions where the same place name gets translated differently). Tolkien knew enough Swedish to be able to read the book, and did not approve, leading to him (and later Christopher) telling the Swedish publisher that Ohlmarks were not to be allowed to do any more translations of Tolkien's (either one's) work. He also wrote a translator's guide for future publishers so they'd be able to get it right.