Puerto Rico ISO 3166-2 code

hello.

i am trying to do a lookup for Carolina, PR using parameters for structured requests:

https://nominatim.openstreetmap.org/search?format=json&limit=1city=carolina&country=pr

However the lookup works only with US:

https://nominatim.openstreetmap.org/search?format=json&limit=1&city=carolina&country=us

According to wikipedia the ISO 3166-2 code for Puerto Rico is PR. I know it's an administrative part of the USA but shouldn't be the primary ISO 3166-2 code PR?

for certain countries it doesn't work at all:

https://nominatim.openstreetmap.org/search?format=json&limit=1&city=Punta+Caucedo&country=do

but works with freeform query:

https://nominatim.openstreetmap.org/search?format=json&limit=1&q=Punta+Caucedo%2C+do