Wait, wait wait.
I realize this is just a cipher and not so much a language but this is still confusing.
In English we use "an" in place of "a" when there is a vowel sound at the beginning of the next word.
So what if you're 'translating' English "a cat", which would you use? As the English "cat" does not start with a vowel, however "oraanj" does.
Since English nouns don't have gender classes, the purpose of differentiating between a and an is simply to add "contrast" (for lack of a better word). For example, in "a apple" two successive 'a' sounds just mush the words together, having an 'n' sound between them makes them stand apart and flow better together.
A similar system could be used for this, but instead of vowel sounds, use 'akr' preceding words that don't also begin with an 'r' sound, and 'yin' for those that do