Yes, if you are logged on to CPDLC, ATC can see everything that is in Route 1 (Boeing) of the FMC.
Two years ago, and a thousand miles off the coast, we got a message from ATC to remove the STAR that we had inserted enroute as we hadn`t been cleared for it yet. I really wanted to tell them to eff off as this is my FMC not theirs and I will use it as I deem appropriate. Anyway, since that time I still insert the expected arival, approach and runway and nobody has told me otherwise.
I generally find in Australian Airports that the STAR clearance is delivered too late to crews to enable them to give a proper brief. Rushed briefings during descent are a hazard and a threat to air safety. If the STAR clearance arrives and is different to expected then change the FMS entries or if the FMS has a secondary/alternate Flight Plan storage and it has already been preloaded with a different runway, checked and briefed it is only a matter of activating and executing.
There is less risk loading and briefing the expected clearance than rushing briefings. I don`t feel there is a significant risk of pilots flying the wrong STAR if the clearance is different to what has been loaded. Any clearance received should be checked against the box anyway.
My two cents worth.