I don't mind it, but I prefer the cases where the "translating" character does more than just repeat the lines for the audience. Lando's half of the conversation does tend to advance it, so that's OK.

Lando: "We've got to be able to get some kind of reading on that shield, up or down."
Nien: [Our sensors are jammed.]
Lando: "But how could they be jamming us if they don't know if... if we're coming."

This reads like a normal conversation. The exception is when the character is also translating for another character — eg. in ESB Han translating Chewbacca's lines for Leia's benefit ("Found him in a junk pile").

Come to think of it, a line I wouldn't mind seeing cut from ESB:R is one of these lines. "The city's central computer told you?" is purely repetition-for-the-audience, as seen if we translate R2's lines based on 3PO's replies:

C-3PO: "How would you know the hyperdrive is deactivated?"
R2-D2: [The city's central computer told me.]
C-3PO: "The city's central computer told you?"
R2-D2: [That's what I just said, stupid.]
C-3PO: "R2-D2, you know better than to trust a strange computer!"

3PO comes across as obtuse and slow; omitting the second line rectifies this. The third line gives us all the information we need to know from the second line, particularly given we saw R2 interfacing with the Cloud City computer and he mentioned the Falcon's hyperdrive (translated by 3PO in a non-repetitive way) then.