Rammy,
The SY CATIS (computer ATIS) is updated by the SY tower staff; it used to be done by the coordinator position or Senior Tower; I'm not sure who does it now; there's a traffic manager there sometimes...
Anyway my suggestion is put in a CAIR report; describing events, time circumstances etc. There have been occassions when the CATIS is broadcasting different info to what is on the display at Directors/ approach Melbourne or Brisbane or even the tower cab itself; faults can occur etc. nothing seems failsafe anymore...
I agree with your sentiment about wind and QNH; they are easy to measure (reading the box) and keep accurate; cloud is different; depending on runway configuration etc the base can be very different for different runways; usually this info is updated based on pilot reports or otherwise is an educated guess at best. A mention of we nearly made a 'go round' because the cloud base is XXX will always get them adjusting things.
I agree with you whole heartedly that the info should be accurate but it is difficult to manage at times; particularly if short staffed or something else dramatic is going on that might not be know to others using the aerodrome etc. It's a matter of priorities I guess and if a 'go round' did occur because of the events you describe then that may be the lesser of two evils from the controllers perspective. You make the decision to land or not afterall... and that's the way it should be.
Bottle of Rum.