"저는 배우들 사이에 서요."
Translation:I stand between the actors.
It does. In English this is idiomatic -- it means you are keeping the actors apart. 'Between' being a preposition of place has to refer to an object between other objects. 'I stand' is not an object. Only an adverb would do. "I am between the actors." This is correct. "Where I stand is between the actors." This is correct. "I stand in between the actors." That's how I'm standing, in a place.
Yes and no... I have thought about this for a while, and because this sentence just uses 에 instead of 에서, in addition to using an inactive verb 'to stand' I think it is more appropriate to translate it as I stand between as opposed to in between. Also, 'between' is more of a preposition while 'in between' is more of an adverb. So take it as you will, it is definitely arguable, but I hope my explanation is helpful.
The difference is 에 and 에서. The first one is used when you are at some place, when you go to some place etc. The second one is used when you actively do an action. Since you are only standing in this sentence, you aren't actively doing anything. You just... stand. So 에 is required. If you would for example eat between the actors, it would be 에서 because you are actively doing something.
joenun beu dul sai ea so yo. only means between not stand between. sai ea soemnida is stand between. The sentence used by duo lingo is too general and does not give the grounds for excluding " I am between the actors" and is not used in this way in Korea. They probably are actually standing in most situations when this is used but the Korean meaning is not that precise. They could use the same sentence when the people are sitting on the ground or laying next to each other at the beach.