Just a little quibble with your point about Tibetan writing - a better comparison would be Modern English written as it was during the Old English period. So like “lord” might be written as “hlafweard”, for example, because it is a direct descendent of that word put through hundreds of years of pronunciation change. English doesn’t come from Latin and “finally” doesn’t come from “ad ultimum”, whereas Tibetan does come from Old Tibetan, the language the script was originally fairly adequately adapted to.