system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] If Peter Quill has a universal translator, why couldn't he understand Groot in the first Guardians movie?

Peter received a universal translator after Yondu took him from Earth, it's brought to our attention when he's arrested in GOTG Vol 1.  
Now, if he had that translator, why couldn't he understand Groot? We know in the MCU that Groot is a language that can be taught because Thor claims to have taken the class, which is why he can understand Teen Groot.  


~~We also know Groot is the last of his kind, meaning not many others would know how to speak his language.~~

Could the translator possibly be able to auto-update and delete languages it thinks are no longer spoken? Or be able to adapt to new languages but had to listen to samples of Groot's language for awhile before it would be be able to translate?   
Could this explain why Peter couldn't understand Groot in the first movie but seems to understand what he's saying by the second?  


Or could this just be a plot hole?


[Edit: Its not stated in the MCU that Groot is the last of his kind like in comics and the cartoon. I didn't think about the differences when I first posted this.]
gpt
All words in his language sound just like the phrase "I am Groot" in English. Since Quill speaks English, it tends to assume people are speaking it unless there's a particular reason to think otherwise. Basically, it's a software bug.