Genres like Fantasy and Science Fiction are notorious for having unusual names. Character and place names help set the tone and the setting of a story. The Lord of the Rings would read a little differently if it told a tale about Bob and Rick rather than Frodo and Samwise.
So we speculative fiction authors do (and should, in my opinion) use or create names the readers may not hear in their every day lives. But how do you know if a fantasy name is too complicated?
I generally don’t struggle with fantasy names, and as a result have a hard time figuring out when a name might be difficult for a reader. Perhaps it’s because I grew up in Watervliet (pronounced WAH-ter-vuh-LEET) in New York, near other places with Dutch and Haudenosaunee names like Rensselaer (depending on who you ask, pronounced either RENS-slur or REN-suh-LEER), Schenectady (ska-NEK-tah-dee), and Niskayuna (NIH-skah-YOO-nah); or perhaps it’s because throughout my life I’ve known people with non-Western names.
So, how can a writer determine if a reader will be able (or at least willing to try) to pronounce a character or place name? One place to start is to use (or create) names that follow the conventions of the language you’re writing in. If that language is English, for example, readers may have trouble with Gaelic names. While both languages technically use the same alphabet, they read letters and letter combinations very differently. Therefore, an English-speaking reader may see the name Caoimhe and try to pronounce it as “Cow-EE-meh” or some variant, when the actual pronunciation is “KWEE-vah”.
Beta readers are a valuable resource for this issue as well. If your betas all come back complaining about the same name, it may be worth reexamining that name to see if it could or should be tweaked.
In my Gaslight Frontier Series, I’ve given my characters Russian or other Slavic names, and based place names on Russian words. Russian uses a different alphabet than English, so some trouble lies with transliteration. For example, the name Alexi could also be written as Alexei, Aleksi, Aleksei, etc. I chose to spell it as Alexi because it was the simplest transliteration.
Some names, though, still give some of my readers trouble. As the author, you have to decide if that will be something you accept or something you change. Only you can make that final determination.