When Claude responds in non-English languages, it now receives explicit instructions to maintain full orthographic correctness, including all required diacritical marks, accents, and special characters. For example, it will no longer substitute "nao" for "não" or "fur" for "für".
Evidence
Orthographic instruction (search for "orthographic" and "diacritical marks")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.