The problem with some of your answers snd explanations is that they too often fail to take inyo consideration thr fact that when conveying a message from one language to another, the rules and idiom of the target language should be respected. It is simply egregious in English to say "shall adults" the expression is "young adults" "little adults" at worst.
I guess we will all have to learn the Smart Phone languages. So far I have recognized the "autocorrect dialect" and the one you seem to be using which is the "tiny keyboard" dialect.
Young adult is a different idea usually meaning 13 to 21 years old (or so), especially for the purposes of categorizing books:
This is talking about precocious children:
So "small adult" does fit here.