I may be wrong on this as I'm only learning like the rest but I think when you use a sentence with a noun like "Tá úll uaim" it means "I want an apple", but when you use it with another verb (in this case éisteacht) it forms a phrase that means "you want to listen". I don't know why it works that way, but it seems to.
Is from you to listen with the stories.
From you expresses the desire to want, It's like asking has anyone seen your phone, you dont have to tell them you want it, its implied by asking if they seen it. Saying something is from you, means you want it.
So what is from you? (to listen) you want to listen.
So it is from you, (to listen), but where? with the books. Leis, and this is why leis is there.
This is a perfectly 100% normal sentence structure in Irish. It is exactly like say "You want to listen to the stories". Dropping the "Leis" would be like dropping the second to and saying "you want to listen [to] stories", in engish,
"you want", expresses a longing to do something, but what? "to listen", the action, but what do you want to do the action TO (not with like irish) "to, the stories".
If you attach the words "from" and "with" to the feelings inside you of from and with, and not the english words, when you hear this sentence it means only one thing in your head, you want to do something, it doesnt seem like it could mean anything else. Its actually very normal, very logical. When you go to translate into english you dont even think about translating literally, because the feelings inside you are of wanting to do something, not of literally from you and with something.
So its perfectly normal sentence, its not trying to trick you, it makes total sense, you cant drop the words to try make it more sense, and it can only really translate to wanting to do something.
Thats about as close as i can get to explaining a "literal" description of whats going on in this sentence.
This sentence is using a phrasal verb with tá and ó, which means "want" - Tá uaibh éisteacht leis na scéalta.
To say "must", you can use a phrasal verb with tá and ar - tá oraibh éisteacht leis na scéalta
(there are a number of alternatives constructions that can be used for "must").