Not really, but that's also a good point! :D In both Spanish and Portuguese, the word "mate" doesn't have a diacritic, but moreover the stress syllable is "ma"

Not really, but that's also a good point! :D In both Spanish and Portuguese, the word "mate" doesn't have a diacritic, but moreover the stress syllable is "ma", not "te". So, even if a diacritic was granted, it should be "máte" rather than "maté".