I'm in NZ and it worked. It gave me US figures and numbers though. And I find there are existing FIRE calculators already out there that are tried and true.
What's genuinely missing for you is NZ tax and NZ Super. So it worked, but you got the generic version.
On the existing calculators, they're good and I use them too. Most are tried and true against US history, which is the one sample where equities did unusually well. That's the gap I was after.