I think they gave you good advice
https://greenharvest.com.au/GreenGardenN ... oilpH.html
The calcium and magnesium are both high but it usually does not affect growth as long as pH is controlled. A pH of 7.4 is not as bad as pH 8.5. But you would want to avoid adding any more Ca or magnesium to the soil
and acid loving plants won't be happy.
pHof 7.4 is high enough to limit the availability of iron which could could cause chlorosis.
If the basis of your soil is limestone, then iron sulfate would do a better job than sulfur in lowering the pH.
Adding an acidic compost if you can find one or peat moss which is organic matter and acidic will help to buffer the pH of the soil so it behaves more neutrally and make nutrients more available.
Steer manure provides slow release nitrogen and organic matter and can help increase acidity over time. It can be added to the peat moss. Do not use chicken manure. Chickens, ie laying hens are fed calcium to help make the eggshells strong, but what goes in goes out and chicken manure can actually raise the pH of the soil even more.
It is not a quick fix but it will improve over time.
As the pH gets range more of the nutrients will become more available and will balance out. A balanced fertilizer was recommended and that is wise for now. If this is grass, that is established you don't really need a lot of phosphorus since that would contribute to building up of thatch.
If you dethatch, aerate and spread the peat moss/steer manure in a thin even layer a couple of times a year, and get a soil test every three years or so until you are balanced, then your phosphorus requirement may not be as much and the fertilizer recommended will change.
Happy gardening in Hawaii. Gardens are where people grow.