Translation:At the movie theater they are presenting a good program.
“One” is more used when talking about something in general, but here it is la kinejo, a defined cinema. In this case ”they” is preferred. Can a native speaker tell more?
"They" is correct. "One" would be wrong here in English, although I can't explain why (native speakers are useless at explanations, I'm afraid!) I think your explanation is correct.
As a native speaker, it seems more natural to me to leave the "one" or "they" out altogether, since we don't know who they are, and the emphasis is on the program, not the (unknown) people presenting it. "There is a good program being presented at the cinema" is how I would say it. But
One is an individual, they is a collective. A movie theatre is a collective, a group of people operating as an organisation.
Sometimes we would say you, but in this case we would probably say "one".
I don't understand why it's "oni" instead of "ili". Can someone please explain?
Oni is like a general they or one as in, In the store, one can find some good food!
So it's like "one" in English, except it can be also for more than one person, right? It's kind of like saying "ones".
"A good program is being presented in the cinema" was rejected, although I had assumed, perhaps wrongly, that you could translate "oni" sentences as passive constructions.