novice1oo – You need to take into consideration the fact that Strata Reports by necessity include extracts on every nut-and-bolt issue that the Inspector / Consultant finds on the Strata File – and whilst that approach is reasonable it’s not always helpful.
What you and every other prospective purchaser then needs to do is to read between the lines so far as is possible, to ask questions of your own Legal Adviser, the Consultants whose Reports are referenced in the Strata Report, the Strata Manager, and even the Secretary of the Plan’s Executive Committee if you can.
In my opinion, and based solely on the information that you have provided ..
The Construction Defect Claim against the Builder could go either way, but as it’s “defect rectification” (unspecified), the works and the costs thereof could be staged if the Owners Corporation needs to fund it.
The compromised fire protection issues are not major, and relate to sealing gaps around the steel beams at the points where they adjoin or pass-through boundary walls, and the placing of dampers (shut-off flaps) in the exhaust fan ducting at those same locations.
BUT ….. (there’s always one) I’d be most concerned about the Engineer’s Report with regard to the corrosion of the structural steel-work within the building, which whilst apparently due only to the absence of corrosion protection at the welded joints at the time of construction, is no doubt a long-term issue (ref: “numerous past reports”) post construction; and as yet unresolved probably due to the cost (?).
I'’m still loathe to advise you about which way to go, other than to say that if you’re still in doubt after making all reasonable enquiries; then don’t do it !!