So I would say Tolkien would have sticked to his way of reducing "au" -> "o" but for non Tolkien names they rather looked that the names would sound best, something stocking like "Thauraug" or something weird as "Thaurog" could never be used and "Thorlach" and "Toriel" don't sound that nice to me... just like "Glaurfindel"
So in short my opinion is that they chose the ones that roll best on the tongue and which have a certain ring to it.
Oh, sorry, I missed this thread! I've always assumed Salo chose not to reduce Tauriel to either Tariel or Toriel because it made it much more instantly obvious what her name meant. (And perhaps for the sound of the name).
'What' isn't actually a relative pronoun in English. We have five of those - which. who, whom, whose, that. 'What' is known as an adverbial that introduces a 'finite dependent clause' or a 'complement clause'. It looks very similar, but isn't. That being said...
Heniog man teithannen? Do you understand what I wrote? Heniog i deithannen? Do you understand that which I wrote? - this looks better.
Then my guess was right, I always used "man" for what in the middle of a sentence...
And btw. I don't know if there is a way to write "more" in sindarin. just say "... ir gerin lû" (when I have time) sav- could be used, but it's too possessive in terms of ownership... anyway what's your opinion on this matter Lore-Mistress?