Universally intelligible sign language
A language like Adso, based on a very small amount of key roots, can be developed into a universally intelligible sign language.
This kind of language could work like Arabic numerals or chemical formulas, which are universally intelligible, despite being pronounced in thousands of different ways.
This is a rough draft of what the characters could look like:
An example usage of the characters in an international airport:
A hieroglyphic typeface has to be developed, analogous to Chinese typefaces using a pinyin input method.