Interesting in NZ we would say half eight; for 8:30. Which when written looks really strange; but it is the shortening of half past eight. But strangely we always say quarter past eight rather than quarter eight.

8:25 would be eight twenty five.
8:35 would be twenty five to nine.
8:45 would be quarter to nine, or more uncommon is just to read out eight forty five.

In catalan it'd be two quarters of nine, usually shortened to quarters of nine (the two, specifically, is implied). You can also add “and five” (minutes) and “minus five", so 8:20 would be a quarter and five of nine, and 8:40 three quarters minus five of nine. 8:05 would be eight and five, and 8:55 would be nine minus five.

In Russian, 5:30 is also "half of the sixth", but I still hate the Danish numbering system (which I have to live with)

Same thing in Norwegian, but that shouldn't be a surprise given how similar it is to Swedish.

I think it's just a European thing because Czech has it too

It is in Dutch.

The hour that starts at 00:00 is the first hour of the day, hence 00:30 is half of that hour, or half [of] one. I think that makes sense. Not like the british who say half one and mean half past one.