"It will no longer be correct to say that something is (a color or similar property). One must say it "seems" a color, as well as to whom. Not "Snow is white", rather, "Snow seems white to me"."

I´d say this is not needed, when people say "Snow is white" we know that it really means "Snow seems white to me", so saying it as "Snow seems white to me" adds length without adding information.

My first fixes to english would be to unite spoken and written english with same letters always meaning same sounds, and getting rid of adding "the" to places where it does not add information (where sentence would mean same even without "the").