Decades in Polynesia

To mitigate the Tongan 50 SNAFU, I posted a list of Polynesian numbers that I consider are overlays on older sytems:

Language - 10 - 20 - 50
Takuu - sinafuru - matarua, rue - matarima, lima
Vaeakau-Taumako - katoa, kharo, dumaa - gatoaelua - gatoaelima
Futuna East - kau, agafulu - kaulua - kaulima
Pukapuka - laugaulu - tinolua, laulua, luangaulu - tinolima, laulima, limangaulu
Fijian - e tini na, sagavulu, - rua-sagavulu - lima-sagavulu
Niuean - hongofulu - tekau - lima fiha
Tongan - hongofulu - tekau - nimangofulu
Rarotongan - nga'uru - rua nga'uru - rima nga'uru
Tahitian - ho'e'ahuru - piti 'ahuru, ta'au, arooato - ?
Marquesan - 'onohu'u, 'okohu'u - tekau - ?
Hawaiian - umi - iwakâlua - haneli
Maori - ka-cahuru, ngahuru, tekau - rua tekau, tekau - rima tekau

The 'proto-Austronesian' number system goes:
10 = *sa-puluq (1 x10) - 20 = *duSa-puluq (2 x 10) - 50 = *lima-puluq (5 x 10)
so, any major variations in the Polynesian numbers (ie non-cognates) must be, by the rules of the game, innovations in the purely linguistic sense.
But in the real world, a retained number-name from an older vigesimal system (above no 10), cannot possibly be a technical innovation.

Even linguists recognise that
French
70=soixante-dix
80=quatre-vingt
90=quatre-vingt dix
are not 'innovations'.

Most of these Polynesian systems appear to be relatively 'modern' constructions:
Only Rarotongan shows a regular series.
Why else should Fijian make 20= 2 x 1 x 10, 5 x 1 x 10?
Why else does Maori rename 20 as 10, in modern times, and then make up a series?
And what does fiha mean in Niuean? Or haneli in Hawaiian?