I've seen that a good choice of multilanguage while keeping a high performance for SEO, would be a duplicated content in a subfolder for each language, but this way every change must be done once for language, which looks a bit weird, at least to me.
Isn't it a string table like to just modify it with new changes, and keep only one version of the website to prevent errors?
By the way, is that the best approach, or there's something better?
Thanks in advance!