That should be the case. As regulations get stiffer and stiffer the amount of area under the "long tail" get smaller. Of course there's always people who want to screech about how more is needed but at some point the tail is so narrow that society just ignores them because the amortized cost per improvement is just so high it's a no-starter.
Accounting for inflation, or without (even approximately)?
https://www.bloomberg.com/news/articles/2023-01-19/japan-s-i...
Loans can also be difficult for foreigners to acquire, so prearrange financing or cash.
The neighbours have been unexpectedly wonderful. Very kind. I live there most of the time and wish to contribute. I actually think it's advantageous to be a (European) foreigner. They realise all the little nit-picks that Japanese do to each other in the service of community would be mostly lost on me. YMMV.
Getting a loan is also fairly easy provided you are employed and have permanent residency (or a spouse who is a permanent resident or citizen). Shinsei Bank (recently acquired by SBI) seems to specialize in loaning to foreigners.
Neighbor situation is highly variable. I have some neighbors who I am quite friendly with, and others I literally have never seen. Typically neigbors will at least be polite, but you do hear horror stories of neighbors quarreling about taking out the trash, snow falling from the roof onto the neighbor's property, etc. My next-door neighbors live with their aging parents, and the grandfather (who has dementia) once shouted at someone who was doing work on my house. And people do tend to gossip, but it's mostly harmless.
What determines the design of ones' seal as a foreigner? Just transliteration?
For less formal seals you can pretty much pick whatever you want. For those I use my family name transliterated into katakana.
I do still see a lot of houses being torn down. But they are more like 50+ years old, and in such a state of disrepair that they are not worth saving.