Region: Council of Constructed Languages
It's a mix of the three but majority comes from the substrate.
The alternation is to determine the light kuipiri and dark kiitenimi (short: kiinimi) numbers, aka even and odd. Dates back to the older Aruz (or Proto-Aruzhin) number system where (except for zero), all numbers are named after light and dark, alternating.
One - Tiinonimi (lit. first of dark)
Two - Tiinoniri (lit. first of light)
Three - Köikonimi (lit. second of dark)
Four - Köikoniri (lit. second of light)
Five - Kuulonimi (lit. third of dark)
Six - Kuuloniri (lit. third of light)
Seven - Naalonimi (lit. fourth of dark)
Eight - Naaloniri (lit. fourth of light)
Nine - Vaikonimi (lit. fifth of dark)
Ten - Vaikoniri (lit. fifth of light)
It gets a bit chaotic after ten.