Is it common for protocol droids to be disallowed to translate the Sith language?

Question

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.

Answer 1

C-3PO states that the Old Republic's Senate passed laws banning droids from translating the Sith language. That would indicate it's a widespread restriction, not something unique to C-3PO.

Fortunately, the protocol droid C-3PO is fluent in several million forms of communication, and he’s stored a copy of the message. Unfortunately, according to C-3PO, the Old Republic’s Galactic Senate issued a hard-coded ban on “forbidden languages.” So he can confirm that he understands the text, but he can’t speak the translation out loud.

The exact line appears to be (from here, with a spelling fix for "runic"):

Finn: Yeah. Where’s the wayfinder?
C-3PO: I am afraid I cannot tell you.
Poe: Twenty point three gazillion languages, and you can’t read that?
C-3PO: Oh, I read it, sir. I know exactly where the wayfinder is. Unfortunately, it is written in the runic language of the Sith.
Rey: So what?
C-3PO: My programing forbids me to from translating it.
Poe: So you’re telling us the one time we need you to talk, you can’t?
C-3PO: I’m unable, sir. I am mechanically incapable of speaking translations from Sith. I believe the rule was passed by the senate...