The rules posted on Choice Hotels sights govern your earning capability. You might notice that on the NW site it says earn miles for "qualifying" stays at Comfort Inn. At the bottom of the page their is a link, in the T & C for Worldperks accrual at hotels it says to ask the hotel how many miles you will earn.
I would say since Choice Hotels say that you only earn NW miles at hotels in the US and Caribean, than you would not earn them in any other country.
Some of the other brands you can earn miles overseas, but you would have to read for which ones. I think Hilton, Marriott, and Best Western allow you to. Not sure of the others.