Looking at this it says it's lossless (Wylie Transliteration).
What if you had sequences like ནག (ng, or is it naga)? Is it lossless because we can guarantee that every consonant (or consonant bundle as in some of the letters) is separated by a vowel? (I don't really know Tibetan yet, so please excuse my ignorance).
IAST for Sanskrit is another lossless one.
So we have:
There's many more that have this (seemingly) same problem. You can write the same thing multiple ways.
So if you had this in the original Sanskrit:
You would maybe transliterate it as:
Then you might do this to go back:
Or any of these combos:
What you end up with is not necessarily what you started with. How do they say this is lossless? Does it have the same property that every consonant/letter is separated by a vowel?
Is there never a "t + h" sound (t followed by standalone "h") in sanskrit, as opposed to a "th" sound (aspirated t)? What if we say there isn't, but then later we discover one? This is where I'm lost, it seems that such systems aren't really lossless.
Can one explain how these are actually lossless? How can you prove that it's lossless, maybe not so far as a mathematical proof, but a thought experiment or something perhaps?
It would also be nice to know which languages have lossless transliterations out there available, I would like to check them out :)