Ye~ea~ah, (NO!)
Untranslatable flag is like a slap on face, when you translate a story from one language to another. No matter what you say, you practically making a new version of it from a scratch, using the original as a base.
(Yes!) You can use a modern technology advantages to instant translate a whole books, like the G-something translator website. But the main problem with that move is, that it actually don't do human like translation who use dictionary book, and instead change every word into a number. Then it do the math magic.
Whoever this is a cheese trap way, that often lead into a too big change of meaning of the text. Sometime, leading into direct opposite, (changing true to false and so on). I talking only on obvious stuff, that shall be easy, but one extra letter or word, here or there and translation errors go crazy. On sometimes, you can say screw this I doing it on my own, but once again: (It cost a time.)
But lets put the working speed up method on side for a moment and look on a more time consuming problem; the Untranslatable thing. Not talking about words alone, but the puns. Then meaning of certain phrases, especially a word play, that in one language can be catchy and cool. Yet while trying to use them in other one, leads into gibberish and lame feelings. That's why, so many foreign phrases are part of different languages, that don't have a proper alternative for it.
Just think about it, you heard that someone got very stupid nickname, that stick because it was so catchy at that moment. Or have a self explaining lore to it. Yet in different tongue, its just a word without a meaning.
So, if I can say, (or lament), for me, it take a time, to reinvent a pun or word play in second language, that the paragraph, the story part, have a meaning. Especially when I, as the person who lead the reader through the story, build on it. So god luck, to anybody who translating a pun oriented character.
Synonyms can be a tricky cats. Of course, its a common that you got the meaning of the word, from understanding the entire line. Yet play with comma, changing the pace, and the meaning can change based on character or scene.
But on top of that, not all readers will for sure know all meaning of synonym words, and the meaning they got, can change based on what they are capable to affiliate with that word or phrase.
Then, there is the worst offender of all; the AI assistant. Let me say; that the filters and modules, can cause a quite of diverse from intended direction. Like when I ask to spell check. But all it take was a little lag, and I got back an AI rewritten version, again and again. It was no longer my story, so we eventually parted our ways.