I don't know if this fits the question, but in Brazil the "Portuguese-Language Orthographic Agreement of 1990" only started to take effect in 2009 (after I was born), in a transition state, and in 2015 it became official and obligatory.
The changes that I still fumble with are diacritics (e.g. "IdΓ©ia" -> "Ideia") and hyphens (e.g. "contra-regra" -> "contrarregra").