It's A Man, An Ewok, And A Baby.

https://docs.google.com/document/d/1XTqm9X6TxRKe6Uq-4QZCf2Guh3LE6GWwVbes71qBlW4/edit

1. If a character is going to use another language, they should have a good reason for doing so every time they do it. Don't chuck in bits of Dovahzul just to show that you can; Za'kiir himself should have a reason to use it. (If he's just showing off, that's fine. If you are, it's not.)
   
   2. If the audience is meant to know something, the author should make it plain. Don't use Dovahzul for important information. If Za'kiir must be speaking it a lot for character or plot reasons, though, you can write the dialogue in English and let the narrative explain that he's not actually speaking English:
   
   "Blah blah blah," he said in Dovahzul.
   
   3. If the meaning of a word or phrase in another language is plain given the context, there's no need to translate it. (And it's always a good idea to make sure the meaning of any piece of dialogue is plain by giving it proper context.)
   
   4. If the audience is not meant to know the meaning of a word or phrase in another language, or can reasonably get by without knowing, there's no need to translate it.
   
   5. If you must provide translations, either do so diegetically (i.e. as Dorano suggested, with further dialogue) or extradiegetically (with footnotes). Mixing the two with in-line author's notes breaks the reader's immersion in the story and is annoying. Diegetic is better than extradiegetic, since it involves less work for the reader.
   
   TL;DR: Avoid the need for translations at all costs, unless you're going to work them seamlessly into the narrative. Otherwise they're just distracting.
   
   ~Neshomeh

However, they require different skills. I would normally just say "Rule of Funny," but it's a bit more complicated than that. Normally, it would make more sense to just mention the language so that people are aware, but translate all dialogue, maybe with a transliterated accent – otherwise, it's difficult and obnoxious for the reader to follow. So I would say if you intend to translate, don't bother with footnotes.

But sometimes, IF you think it'll work in text, it can be more fun to leave that dialogue completely untranslated, and let the reader figure it out from context. An example, using my own agents:

"I call this meeting to order," Mohan said, giving a meaningful look at his fellow Cafeteria workers. "All present and accounted for?"
"Aye."
"Rrrnn."
"Good. First order of business– the Agents are complaining about the sentient mold demons in the soda machine again."
"Nnngh ernch, ¥#%••§ warhesch," Jof replied.
Mohan suppressed a snort of laughter. "Don't hold back, Jof. How do you really feel?"
"He's right," Lynn said. "They're always complaining about something. If we get rid of the mold demons, they'll just start grousing about the arsenic on the silverware or something."

----

You see what I mean? A footnote would 1) break the flow of the text, and 2) be less funny than whatever the reader imagines. It's like the rule of horror movies. The more you leave to the imagination, the funnier it is. But if you think the dialogue is central enough that it needs to be translated, I would strongly recommend that you put the translations in-text.

...unless it's important what we understand what Za'kiir is saying. If it is, add the translations to the text - footnotes are a pain.

So, something like this...

Zakir: "(Words in Dovahzul)"
Partner: "What?"
Za'kiir: "(Translation of what he just said)"

The translation doesn't have to be word for word (in fact, given how Dovahzul works, it probably shouldn't be), but the gist of what Za'kiir is saying should be made clear.

(Now excuse me whilst I fangirl, I absolutely ADORE the Elder Scrolls series.)

Try not providing translations to the readers. If it doesn't work, you can change it.

If it's just a smattering of words that the reader can figure out their meaning, it's fine to just include them.

If he's talking to someone who will reply, see if the dialog works as a one-sided telephone conversation.

I'm not sure if this is correct writing, but I have seen fanfiction where a character says the non-english stuff and the translation directly follows.

Be careful with footnotes, they are annoying when they get too far away from the text that they are referring to.

If he talks like the Dovah themselves — ie, in a way that the Dovahzul is just added flavour — I think it's OK to leave it as-is. OTOH, if it's actually important for understanding what he says, use footnotes. In that case, though, use it sparingly because having to continuously refer to footnotes in order to understand a character's dialogue is a royal pain.