I've quoted the article. The first arrival has to filed and then doesn't have to be done again if returning. It's not only written in English; it's a confirmed fact. If you actually live in Chiang Mai, go ask CM Immigration. I have - still got the same TM30 I filed in 2019 and have been out of the country and returned in that time since they changed the rules in 2020.
The first arrival, not returning. Which part of this is hard for you to understand? Directly from the article - "The Immigration Bureau has changed the reporting frequency to only when they arrive. They do not need to file the reports again if the guests leave the premises only temporarily and then return, or when they have multiple-entry visas or re-entry permits."
And there are now multiple people, myself included, who have done this and confirmed with CM Immigration that this is case.
If you want to talk about policies, it changed in 2020 - see the link below. While noting that not all immigration offices do this, Chiang Mai Immigration does - at CM Immigration, you don't need to file a new TM30 when you've been out of the country and are returning to the same address, as long as it's not a new visa.
Other than you're a Kiwi, I can't work out much about you. But I can tell you this - real estate doesn't work the same here in the Land of Smiles as it does in NZ and Aus. Tread with severe caution and whatever you do, don't invest in Phuket.