How about gonna, gotta, kinda?
Want to and Wanna, both words mean the same, the intention or liking of something.
Wanna is the contraction for Want to, and is used in a more coloquial speech than Want to.
Both words are correct and used in English. Usually, "wanna" is more colloquial.
Suppose you have audios that say:
"I wanna go to a party tonight! Let's have fun!"
"Excuse me sir. I want to order a glass of wine".
You should transcribe:
[00:00:00] I wanna go to a party tonight! Let's have fun! ✓
[00:00:00] Excuse me, sir. I want to order a glass of wine. ✓[00:00:00] I want to go to a party tonight! Let's have fun! x
We should not substitute "want to" if the speaker says the contraction "wanna" and vice-versa. Remember that we must transcribe literally, and this also applies to colloquial contractions.
Sometimes pronunciation can be tricky, so you may need to play a few times the same audio trying to figure out the way it was mentioned.
Since we have other colloquial contraction, this rule not only apply for Wanna or Want to. It's the same for Gonna / Going to, Gotta / Got to, Kinda / Kind of, etc.