I don't know what you are doing with your calculations monster however you appear to have mixed calendar years with financial years. The wage rises that had generally occurred on 1 Jan will move to 1 July so the "year" rises are measured in is now the financial one.
As for the difference between the back half of years 2 and 4, it is as follows. Year 2 in your calculations ends 31 Dec but you know already that there is no rise on 1 Jan (because they have shifted to mid year). It is a known 0. Year 4 however concludes and we do not know what the outcome from 1 Jan would be because you will be ready for a new EA.
Fedsec, we'll have to agree to disagree. I annualised the pay rises by both calendar year and financial year and assumed zero for the last half of FY2019. In my view, half of a half is a quarter, not a half. But as I said, I'm just being pedantic, and I'm comfortable with the price for peace, stability and 65 jobs restored.
We'll wait and see what happens in Jan 2019. Unfortunately due to previous history I have little trust in the company, and I won't be counting my chickens before they're hatched.
I do however have faith that my association is working in the best interests of all its members, and thank you all for a job well done.