I'm reading the beautiful The Expanse series, and I'm currently on book 3, Abaddon's Gate. I am reading the Italian editions (I don't have any problem about reading in English, but it's my main language and the Italian publisher set a huge discount on all of its catalogue, so I grabbed all of them)
I noticed that besides the regular series of novels, there are also some short stories and novellas set in this universe. These short works were not (yet?) translated, so at the moment only the English editions are available to me.
I'm curious if these complementary works are a mandatory read, meaning if they contain details that are necessary to fully understand what happens in the main books, or if they provide just some background and could be considered only accessory material, that can be read anytime.
Since I've already started this series in Italian, I'd like to keep reading in this language, for the sake of consistency. But I need to know if their content is too much important to skip it and read them later, in this case I could also consider the English option.