How do もう and けど work in the bold sentence?
I think it means something like "but a little bit detailed book would be better" but I'm not sure.
Also, I don't understand how もう works here. According to this post もう has 2 meanings, and the one that fits here is "additional". So, the sentence would be something like "but additional a little detailed book would be better". To me it looks like the customer was not satisfied with what the seller shown him, therefore he wanted to get another book. Or did he want to buy 2 books (the one that the customer offered and another one)?
Also, I would like to know whether けど is really a thing here and has to be translated or not. As I read here, sometimes it can be used as a softener.
I think I get the general meaning of the sentence but I would like to know how it works.