The best typeset books I've seen in Devanagari (a non-Roman script, used for Sanskrit, Hindi, Marathi, Nepali) have been typeset with XeTeX (XeLaTeX). Of course

The best typeset books I've seen in Devanagari (a non-Roman script, used for Sanskrit, Hindi, Marathi, Nepali) have been typeset with XeTeX (XeLaTeX). Of course this involves other system libraries like Harfbuzz to handle the kerning and measure widths of individual words, and leaves some of the complexities mentioned in the post to the user, but the Knuth–Plass algorithm from TeX is still what is at the heart of it, for breaking paragraphs into individual lines. Take a look at TUGboat and the TUG conferences or the TeX.SE website to see it being used for many languages and scripts (including Arabic, Hebrew, etc). TeX is also big in Japan it appears, and they maintain their own variant engines (ptex, eptex, uptex, euptex).