A young cadet surveyor of planets fights an evil force that has infiltrated the League of celestial nations for the purpose of extracting and transferring the life force of people to their own dying population.

The concept is interesting but I feel that this logline has missed the mark.
When I break it down you have:

Flawed protag: young cadet surveyor
Main Action: fights an evil force
Reason for Action: infiltrated the League of celestial nations
Introduction of antagonist force: evil force…extracting and transferring the life force of people to their own dying population.

First off, it’s okay if the protagonist does not have an arch. If they do have an arch, you should find out what value system they will gain at the end. The protagonist at the beginning should be the polar opposite.
That’s the first piece of the puzzle [Flawed Protag]

The second piece is the inciting incident. There are a few different theories as to what event the word describes, but from what you’ve shown so for, I think the Pixar formula would work best.
Everday the character does this. Until one day this happens, Now the character does this…
If the protag knew that he was not sposed to see what he saw, then that might be the Inciciding incident. If the character was oblivious until he was punished for what he saw then that event might be it.

The next step to the logline is the main action. It may be better to skip that for now, instead focus on the ending. What is the main event that everything in the story will lead up to? You have to be specific with this. Don’t focus on defeating Sauron, focus on destroying the one ring. Sauron=the evil galactic empire. Once you have that event, try to express the actions taken to get there in as few words as possible. Also, try to express the immediate stakes if the character fails.

Once you have these elements try to order them [Flawed Protag] [Inciting incedent] [Main action]. These elements have to be clearly stated.
The stakes and the story goal should be implied if not directly stated.

I don’t know your story, but this is my example:
When a cowardly off-world surveyor learns his supervisor is involved with treason on a galactic scale, he must search for the evidence to bring his deads to light, before the League of Celestial Nations descends into civil war.