Where did Leia Organa learn Ubese?

Question

A separate question asks: What language does Leia speak when disguised as bounty hunter Boushh?

Where did Leia Organa learn Ubese?

And for what reason would one want to learn this impractical language?

Answer 1

This will require us to delve into Legends and speculate somewhat.

Leia is given Boushh's armour during the events that happen in Steve Perry's Shadows of the Empire when she and Chewbacca are attempting to infiltrate Corruscant.

The clothes stank. Leia wrinkled her nose at them.

Guri said "They belonged to Boushh an Ubese bounty hunter. Boushh was quite good at the trade. He did a lot of contract work for Black Sun. He ... retired recently."

"As it happens I speak a bit of Ubese" Leia said

"We know. The costume is not a coincidence."

So we know Leia already knew Ubese before the events of Return of the Jedi. This rules out a crash course on Rosetta Stone prior to the rescue mission.

Why did Leia know Ubese?

Nothing but speculation here:

The most likely reason would be she was a Princess, daughter of an Imperial Senator. She would be trained in many languages.

Why an obscure language like Ubese?

Maybe it would be good for code talking, especially if she knew the sign language Ubeninal too, or maybe something about it just appealed to Leia's curiosity.... maybe some subtle force prescience made her learn it "just in case".

Gaining the armour and being able to speak Ubese gave Leia a perfect ready to go disguise when they were formulating a plan to rescue Han Solo.