In case you'e wondering, here is a transcript of what I tried to say in my lolwtf Avian language and what I "believed" it should have meant. It's totally random with no context that I just came up within 10 seconds so sorry if it annoys your linguistic nature.

1. Ja Tro Pa'tui Abatso - Just in time for the meeting
2. Mor Balaten - It's Mor Balaten from XCOM 2 because I felt like saying it
3. Oh? Yoho'is Kabahoh - Oh? It's you again
4. Kesa'mu Nentorr Kabitol...Va'kusin - We are always watching...Remember that.
5. Shearos Ka'chorus Ohhohohoh - That's a very weird voice you have...hahaha <Yes I cannot stop laughing to myself when I recorded this>

Thankfully altering the voices made the quotes sound less..awkward and dumb.

I may move the Skyrim Dragon voices from Plantoid to the "Dragon" species from the free DLC anniversary pack, can someone confirm that it has it's own sounds? I never personally encountered them in my games so I am not sure.

Yes, the dragon has its own voice. It's some kind of loud sniff, as opposed to the hissing of other reptilians.
The other anniversary pack species also have their own voices - the larva has clicky humming without much attack, and the peacock has bird sounds with wing flapping.

You can test these by making an empire with the portrait, then playing as them, and using the console to switch to another country and contacting your empire.

I suggest a humanoid language, "Simlish" (Sims games). And another, Tusken Raiders for perhaps mammals, like the boar.