A plot point in The Rise of Skywalker is C-3PO's insistence that while he can read text written in the Sith language, his programming forbids him from translating it for others.
Is this restriction a common one in the Star Wars universe? That is, do most protocol droids come out of the factory programmed to understand Sith but with a block against translation, or could this be something that Anakin and/or Captain Antilles intentionally added in for some reason?
It stands to reason that Anakin (who has been an expert droid technician since childhood) might have chosen to put a block on C-3PO's ability to translate Sith in order to prevent his wife from discovering his increasing interest in the Dark Side, but this doesn't match what we see on screen - his initial Sith education seems to come directly from Palpatine rather than independent research into Sith texts that might accidentally get left around where Padme could see them. It also doesn't explain why this block wouldn't have been removed when Captain Antilles wiped C-3PO's memory after Anakin's fall.