That is the fun thing about English. There isn't really a single right way to speak or write it. It is defined by common usage. As long as your audience understands you, it is correct.

As someone else pointed out, loan words often have accents. At what point does jalapeño become en english word? There is no other english word to refer to the pepper, therefore it is now an english word and therefore english words can have diacritics.

The closest thing we have to a source of truth for the english language is the OED. It isn't prescriptive, it just lists how words are used rather than how words should be used.

Jalapeño is in the OED with the tilde https://www.oed.com/dictionary/jalapeno_n?tab=factsheet#1253...