On Writing for a Reader Who Will Read You Translated
I did the arithmetic on my own readership once, out of curiosity, and the honest number is that most people who will ever read one of my novels will read it in a language I did not write it in.
That fact changed how I draft, and not in the direction most writers expect. I did not start writing plainer out of modesty. I started asking, sentence by sentence, what percentage of a given line's effect depends on the specific sound of the language I happen to be drafting in, and treating any answer above a certain point as a cost I am imposing on almost everyone who will eventually read the book.
The translation-proof sentence test
Here is a line from an early draft: "the boat bobbed, brackish, broken." The alliteration does real work in English, three hard consonants knocking the sentence forward the way the boat itself is knocking against a dock. Run that sentence through any translation and the alliteration is gone, because it was never about the boat, it was a coincidence of English consonant sounds, and no other language owes English that coincidence. What survives translation is only "the boat rocked, salty, damaged," three adjectives with none of the percussion that made the English version worth writing in the first place. For a reader in French or Arabic, I have written a boring sentence and charged it as if it were a good one.
The test I now run before keeping a sentence like this: strip the sound-level effect and read what remains. If what remains is still doing work, an image, a fact, a piece of characterisation, keep the sentence and enjoy the sound as a bonus for readers of the original. If what remains is inert, the sentence's entire value was a private arrangement between me and readers of one specific language, and I am choosing, deliberately, to write that sentence for a minority of my eventual readers while charging the rest full price for nothing.
What this looks like in practice
For the boat, I rewrote toward an image rather than a sound: "the boat had the look of something that had given up arguing with the tide." The sentence has no alliteration left, and it is doing more work than the first version in every language, because the effect it depends on, a boat's stillness read as an argument the boat lost, survives translation intact. A translator working from this version has something to carry across. A translator working from the first version has to either invent new alliteration from nothing, which is its own kind of theft, or hand their reader a flat sentence and hope nobody notices what was lost.
The case against this
Writers who take real pride in the music of their sentences tend to disagree, hearing this as an argument for writing down to an imagined lowest common denominator, optimising every line for portability the way a product gets optimised for a market it has not entered yet. I understand the discomfort, because there is a real version of that failure. A manuscript with every sentence flattened to whatever survives translation reads like a manuscript with the personality sanded off it, competent in every language and alive in none.
The honest reply is that I am not proposing zero sound-level writing. I am proposing that you know, sentence by sentence, when you are spending that currency and choose the moments on purpose. A handful of sentences per chapter can afford to be untranslatable, the way a handful of idioms per chapter can afford to be borrowed rather than invented. What I am against is doing this by accident, dozens of times a book, because a sentence sounded clever while drafting and nobody stopped to ask whether the cleverness was the sentence's only asset.
The reader you are actually writing for
Once you accept that most of your readers will never hear your sentences the way you heard them while writing, the question changes from "does this sound good" to "does this still work once the sound is gone." That second question is harder to answer honestly, because it requires admitting that some of your favourite sentences were never about the story, they were about you, enjoying a coincidence your own language happened to hand you. Keep a few of those. Know which ones they are. Do not mistake the enjoyment for the achievement.