Some interesting observations.
There is more than one way to look at whether Manuka has become simply a generic name, similar to how tea tree or blue gum might be used by some.
Others will probably decide if Manuka is indeed a unique product label or a name in more common use. So far the NZ honey industry has failed to gain a unique trademark in other places, (per the original post) in the UK or EU.
Perhaps they could also trademark as ‘NZ Manuka Honey’.
Agree there are plenty of alternate brand descriptions the Australian product might choose instead. In particular if Australian species of leptospermum can be shown to have higher levels of the active ingredient than the Kiwi version. Would it then be wise to have the same branding as the inferior NZ product?
Aussies seem to refer to a wide variety of plants as Tea Trees. Just not those of Genus Leptospermum, but others from the Myrteceae Family including Melaleuca, Sannantha, Baeckea, Babingtonia.