Council surveyor asks overkill on verandah roof rafters. And can I use a ridgeboard?

Hello! Long time lurker first time poster, I come here for all kinds of things from waterproofing to rock wall masonry, I am an advanced DIYer. But now I have a question that I simply can't Google.

I have plans for a Deck and polycarb roof approved by council but my draftsperson turned out to be unqualified and not able to work out spans any better than I can. Council was the surveyor and I was the final draftsman. The plans were approved but I think there is bad oversizing of the rafters and ridge due to inexperience.

The deck is now fully built and passed inspection already and looking amazing. Its time to buy the next load of timbers. I have no questions about the beams at 2/190x45mgp10 which are clear to understand, but I am completely unsure on the definition of a rafter span, and unclear about why council are happy to mix up a ridgebeam and a ridgeboard.

You can see below the image of what I am trying to build. The total span 'c' is 6000mm, and the distance between 'f' and 'e' is 3000mm.

For the purposes of span tables in AS1684 is 'A' what is defined as a single span? Assuming the unit 'b' is fully unsupported.

The unit to be installed in the location marked 'b' is named in the plans a ridgebeam and the council surveyor specifically asked me to upgrade it to 240x45. but I have been studying the AS1684 and this beam is not a beam as its fully unsupported, making it a ridgeboard right?

Council plans state that the rafters and ridgebeam need to be 240x45 each but this would span 7200mm x2 total right? like some 14meters wide? (no wind load) meaning its waaaay oversize?

I want to use 140x45mm MGP10 TP rafters, and a 190x35mm ridgeboard so the 140s sit nice on the plumb cut on the 190 boards. Will this work? Or even if I could get help understanding what a rafter span is exactly I can work it out myself.