Who pays for external water damage from a building defect?

I have a friend who bought a strata unit in Sydney and lives in it (about 18 units in the block).  After the recent wet summer the bedroom became an unpleasant place due to high levels of mildew.  Six weeks ago the skirting boards were discovered to be falling apart and further investigation showed that water was underneath the carpet, damaging it and the floorboards.  For health reasons she has been sleeping in the lounge.

She reported this to the SM and, after issues with a deliberately obstructive little Napoleon on the EC, finally managed to get an engineer out to investigate the problem. The report showed that water was pooling in raised flower beds outside (large concrete ones built in as part of the complex) and because of insufficient drainage the water was held against the external brickwork for a long period of time.  This then seeped through into my friend’s unit.

I have lived in strata for 20 years (been on the EC most of that time) and am bemused that this issue has taken so long to resolve. I’d like to ask for verification on aspects of this issue:

1) Is the OC responsible for the cost of engineer reports and the work needed to fix the problem?

2) Is the OC responsible for the cost of fixing the inside of the bedroom from the water damage?

3) Is the EC required to deal with this issue immediately?

I am assuming the answer to all three is ‘yes’ but welcome the knowledge of those more experienced.