[dragonwriter]

> All the letter (and sounds) used NEED to be pronounced, the same way, for native speakers of English, French, Russian, Spanish, and also various major (eastern) Asian languages.

Do you mean all the phonemes need to be present in all of the referenced languages, or that they need to be indicated by the same letter or letter combination in each language? Because, the former doesn't leave a lot, and the latter is even worse, even if you choose the most popular current transliteration for those languages for which the Latin alphabet isn't the usual one.