I am based in the USA and I write for myself with hope that a larger audience might find my words and storylines to be of interest to them. Because I have that hope, I am always thrilled to get reviews, and happy to get comments. Also because of my location I write using a US vernacular and try not to choose terms that are too far outside of the commonly used words for my nation. I don't use "boot" instead of "trunk", if I'm writing a story set in modern times I don't have my young male characters wearing shorts for normal and daily attire because in the US they would probably be wearing long pants (depending on climate), and I don't have my characters eating "bangers and mash" because that meal usually would not be called by that name here. I choose my terminology because of where I live.
That said, if I would be writing a story where my characters would be living in London or in another part of England, I might use terms more commonly used in that area, but I know I don't have a good handle on all of the nuances and I would ask a few online friends to take a quick read-through and see what I had wrong. If I need the true feel of a different culture, I cannot get that from the outside looking in. I need an expert, someone immersed in that culture, to take a look for me.
So, with this established, what about fantasy worlds? On one hand we have elves, dragons, magic. On another hand we have galactic empires, gravity-defying devices and sentient androids. How do we approach correct terminology for societies that have never actually existed?
That is the beauty of original fiction. All of a sudden you can make a world. You can call vehicles hovercraft, anti-gravs, or simply horses. You can fight with swords or with blasters or ray guns. You can construct your world as you see fit, and you can construct your vocabulary to match. Tolkien did this by inventing languages and forming cultures using the languages, eventually ending up with realms in which new readers lose themselves every day. The world he created is rich, multi-layered, and ever-surprising; it's a multi-layered chocolate cake of pure delight. If the worlds that we are creating end up to be even one bite as pleasant, then we're succeeding as authors of fiction.