Thanks! Here are the conversions, as I currently have them.
Tonga -> Murihiku (This was a really, really lazy choice on my part.)
Waitaki (See below)
Okahu
Timaru -> Tihi-o-Maru
Rangiora -> did the province swap with duchy naming. It's better than my placeholder name anyway.
Paparoa -> Kawatiri (Sounds better

)
Tahwitinui -> Wairau (Shorter is better, given the province size)
-----
Pakuratahi -> Te Upoko
Wairarapa
Wanganui is awkward at the moment, see below
Pahiatua -> Waipukurau
Patea
Taranaki
Waikato
Tokoroa
Whitianga
Tamaki -> Támaki (It does

)
Kaukapakapa -> Whangarei
Parengarenga -> Aupouri
My duchies are a bit more awkward, because modern NZ regions really don't help, for the most part. Most of them, especially where I want them to be, are European names.
From bottom to top, most (all) of these are placeholders:
Otago (?)
Waengahari -> Waitaha (Even lazier than Tongu)
Motueka (???)
---
The southern part is currently Manawatu, though it doesn't fit too well. The rest, I have no idea. The 'middle' duchy I just have as Taranaki at this point. No idea where I'll go from there, is there a Maori word for the entirety of the long peninsula at the top?
EDIT: I've also placed the Maori in the polynesian culture group, given them their own religion in the catch-holder pagan group and gave each island it's own culture (not sure if they should be a single culture, or as is, or more). The cultures are boringly named Tonga (South) and Tuaraki (North), because I'm <sarcasm>
an original and creature person with a deep knowledge of the maori language and culture </sarcasm>
thanks for helping.