They can do whatever, I hope the sanctions are not lifted. No negotiations with the US puppet states.
The sanction won't be lifted easily, I can assure you. Just look as what happened to Norway for how long.
At the minimum China's demand are 1. Lithuanian government make official statement accepting the responsibility and reiterate adherence to "one china" policy. 2. rename the office.
The 1st demand is probably too "humiliating" for the current government. In Norway's case, it was the new prime minister from opposition acknowledged the fault of its predecessor, much easier to do. So I think the current situation will last until next election or resignation of current Prime Minister for whatever reasons.
China may seek a higher price for Lithuania, also serve as a warning to the rest. That is totally close off this office. If the office was named properly from the beginning, China would not have bothered. But Lithuania doing the whole naming thing in a show to the world. Allowing it just returning to where it should have been even with apologies is making an example that they can play like this and get away with an apology. It is not like some decade ago that China can be satisfied by such "one step forward and one step backward" game, time has changed, the bar has raised.