There’s a lot that goes into accents but a good starting point is to identify all of the phonemes that exist in the learned language that don’t exist in the speaker’s native language. Those are ones a language-learner is likely to have trouble with.
As best as I can tell, the phonemes that exist in English but not Quenya are tʃ, dʒ, ʃ, ð and ʒ (and θ, obviously, if we’re talking Exiles, but Tolkien says that they’d have been familiar with the sound anyway from Vanyarin and Telerin Quenya.)
(For people who don’t work with IPA much, those sounds are ‘ch’ like in chip, ‘j’ like in ‘jump’, ‘sh’ like in ‘ship’, ‘th’ like in ‘them’, and ‘zj’ like measure.)
So I’d write a Quenya speaker trying to learn English as having a hard time with those sounds. Often when learning a language with unfamiliar phonemes, speakers will round to the nearest one they are familiar with, which is why lots of non-native English speakers say ‘z’ for ‘ð’ (voiced ‘th’ is relatively uncommon in languages).
Sindarin has both ð and θ, is missing tʃ, dʒ, ʃ and ʒ like Quenya, and is additionally missing z.
So if you’re talking to an Elf in English, and they have an accent, you could easily guess whether they’re a native speaker of Quenya or Sindarin by how they pronounce the sentence ‘They zoomed chartered ships to the jump.’ Quenya-speaker will hit the ‘z’ but have a terrible time with ‘they’, Sindarin speaker can say ‘they’ just fine but might try ‘soomed’ or ‘thoomed’ for ‘zoomed’, and both of them will have a miserable time with the rest of the words.
This is a comedy sketch waiting to happen
MisbehavingMaiar: Tumblr Archive 