My understandings, as one very familiar with Indic scripts, very familiar with Unicode in general, but not a CJK user, so please correct me if I’ve blundered:

My understandings, as one very familiar with Indic scripts, very familiar with Unicode in general, but not a CJK user, so please correct me if I’ve blundered: • Indic scripts need the renderer to support complex text shaping, or else the text will generally be illegible, as though you were drawing your letters wrong, stacking some vowels on top of each other, and other nonsense things like that. As an example, if you’re not familiar with Indic scripts, see the code points used to write my name in Telugu, and how they contribute to the rendering: https://temp.chrismorgan.info/%E0%B0%95%E0%B1%8D%E0%B0%B0%E0%B0%BF%E0%B0%B8%E0%B1%8D.svg https://temp.chrismorgan.info/%E0%B0%95%E0%B1%8D%E0%B0%B0%E0.... It’s basically “letter ka, delete the vowel, letter ra, delete the vowel, add vowel i, letter sa, delete the vowel”, but the “kri” will normally be joined together into a conjunct, with the vowel sign drawn on the first consonant, and the second consonant being drawn in a completely different way from normal, which may even affect layout by font—the r conjunct can be a semicircle below, as in that font, but it can also be a curve beginning on the left, shifting the k to the right. (Me, I like the curve style for no particular reason, but the semicircle seems more popular these days. If this concept seems weird to you, reflect that English has allographs too <https://en.wikipedia.org/wiki/Allograph https://en.wikipedia.org/wiki/Allograph>, though mostly not particularly affecting layout.) • But as regards line breaking, Indic scripts are much the same as English. • CJK shaping/rendering can have a bit of complexity because of Han unification <https://en.wikipedia.org/wiki/Han_unification https://en.wikipedia.org/wiki/Han_unification>, and definitely has a lot more nuanced stuff like mixing horizontal and vertical writing modes, and what to do when you mix scripts (which happens much more than with Indic scripts), especially digits, and especially when combining vertical and horizontal. But if your engine doesn’t support any of this, your document should still at least be fully intelligible—just uglier. • CJK line breaking is awful: where most languages have settled on using spaces to separate words, most CJK languages mostly don’t (Korean does, I believe), and so you pretty much need to know the language to avoid breaking in the middle of words. So you end up things a bit like hyphenation dictionaries to try to do a good-enough job of it. Again, if your engine doesn’t support this, your document should still be intelligible—just uglier.