Slightly off-topic, but still re Threepio: I think it makes sense to cut his memory being erased in RotS and in ANH edit his dialogue with R2, so that when he’s talking to Luke about R2’s mission a viewer could infer that they’re sussing out whether Luke is trustworthy.
That is the long version of making it clear in TRoS that his restored memory includes 1-3 though…