You could just use Translation Convention
and render what they say in English but have it that, due to the nature of their language, contractions aren't possible (they find the concept "alien" but can use them when speaking English) thus rendering their dialogue in their own language without contractions but using them when they or anyone else speak English.
You can also point out from their viewpoint that they find English word order "unusual" and have to remember to put things in the right order for English (perhaps the occasional mistake in their spoken English to further differentiate from the English translation of their own language) or lament that English lacks words for certain things (such as the appropriate words for familial relationships which would be clear in their language but "dumbed down" to "aunt", "uncle", "grandfather" in English, and perhaps make some
prone to say "my mother's father" in English) and find English has far too many words for other things.
Do make the differences go both ways, though - their language will be rich in some areas and poor in others, by comparison, English will be poor in some areas and rich in others. It'll all depend on priorities.
Niven, in one of his Tavern stories has one of the aliens chide a human (speaking her language) for using the wrong form of "your" - the one denoting "part of you" rather than "something you possess" - as their possessives are extremely precise, while we only have the one. (The alien observes that the difference may explain why humans will fight to the death over "their" house or "their" money as if they were fighting a threat to "their" arm, while her race distinguishes between that which is part of them and that which is merely a possession).
Your aliens might, due to a quirk of their nature, have a billion different names for something we deem unimportant and yet wonder why we seem to have a billion different names for clouds or killing someone.
limyaael has a page on it here: http://limyaael.livejournal.com/154329.html
edited 28th Feb '13 3:56:40 PM by Wolf1066