What are your difficult to pronounce names?
Which Name is Hardest?
naming - Is it better to avoid names with a difficult pronunciation in Middle Grade fiction? - Writing Stack Exchange
Hard-to-pronounce names: how is your experience?
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Does anyone have a name that they struggle to introduce themselves with? I posted about mine previously but I often have to spell it out or repeat it a couple times
Short answer: definitely, absolutely, wholeheartedly 3.
Long answer: Sir Terry Pratchett wrote somewhere that since he was reading a lot as a child, when he was little there were many words he knew only in writing, but had never heard spoken. For example, it was years before he learnt that "ogres" were not pronounced "ogreees". Having a large vocabulary that he couldn't pronounce correctly didn't harm him in any way, nor diminish his joy of reading, but instead excited his imagination. Pratchett then proceeded not writing down to children when he himself wrote for a younger audience. Exciting kids' imaginations is something you're trying to do, right? Then go for it.
Why does it matter that a child wouldn't pronounce a name correctly? So they'll pronounce it incorrectly - it would still sound foreign, look foreign on the page, and evoke the sense of "exoticism" that you're looking for. Furthermore, a child wouldn't know that they're not pronouncing the name correctly. So how could it impede their reading enjoyment? Being 8-12, I was reading Hector Malot (at 6), Jules Verne (at 8) Alexandre Dumas (at 10), and Victor Hugo (at 12). I did not learn until around age 12 that the stress in all the French names is supposed to go on the last syllable. It did not affect my reading pleasure in the slightest.
A pronunciation guide would be helpful. Not being a native English speaker myself, I do not know to this day how one is supposed to pronounce many Irish names. I resort to googling their pronunciation, when I'm not lazy. Tolkien is one example I can think of who gave a detailed pronunciation guide.
Edit:
Found another example of hard-to-pronounce names in children literature for you: In Diana Wynne Jones's Dalemark Quartet, there are names like "Cenblith", "Mayelbridwen" and "Ynynen".
I'm also going to agree with the third suggestion. The idea of a pronunciation guide is a good one, and you could do as others have done and make it part of the dialogue (for example "My name's Shawn, but it's spelled s-e-a-n"). Susan Cooper did something similar with Welsh names in "The Grey King".
I know that this example might be aimed at the upper end of the age range you've suggested, but many children read books aimed at people above their age, and learning new words is part of the adventure. The counterpoint to this is that what many children really hate is people making things too simple for them Because They're Only Young.
As Galastel mentions, it really doesn't matter if people get it wrong. For years I pronounced the name "Honoria" is if it was a disease two very close friends might share, and I've heard that there might be some quite popular books around with a character named "Hermione", which also has potential to be a tricky one. But I still get a small thrill of discovery when I encounter a name I've not heard (or read) before - it's one of the reasons to keep reading.