Here's what I've tentatively decided on:
NORTH AMERICA - Canada and the United States
CENTRAL AMERICA - Costa Rica, Cuba, the Dominican Republic, Guatemala, Jamaica, Mexico, Panama, and Puerto Rico
"FORESTED" SOUTH AMERICA - Brazil, Colombia, Paraguay, and Venezuela
"MOUNTAINOUS" SOUTH AMERICA - Argentina, Bolivia, Chile, Ecuador, Peru, and Uruguay
NORTH-WEST EUROPE - Belgium, Ireland, the Netherlands, and the United Kingdom
SCANDINAVIA - Denmark, Finland, Iceland, Norway, and Sweden
FORMER SOVIET UNION - Azerbaijan, Estonia, Kazakhstan, Lithuania, Russia, and Ukraine
CENTRAL EUROPE - Austria, the Czech Republic, Germany, Hungary, Liechtenstein, Poland, Romania, and Switzerland
MEDITERRANEAN - Bosnia & Herzegovina, Croatia, Egypt, France, Greece, Israel, Italy, Morocco, Portugal, Spain, Tunisia, and Turkey
WEST & SOUTH-WESTERN AFRICA - Botswana, Burkina Faso, Ghana, Namibia, Senegal, and South Africa
EASTERN AFRICA - Ethiopia, Madagascar, Malawi, Mauritius, Mozambique, the Seychelles, Tanzania, and Zambia
MIDDLE EAST - Kuwait, Oman, and the United Arab Emirates
SUBCONTINENT - Bangladesh, India, and Sri Lanka
SOUTH-EAST ASIA - Cambodia, Indonesia, Malaysia, Singapore, Thailand, and Vietnam
FAR-EASTERN ASIA - China, Japan, Mongolia, South Korea, and Taiwan
PACIFIC ISLANDS - Australia, Guam, New Zealand, and the Philippines
I'm really not sure how to quickly describe the two South America categories - like, I see the "forested" countries as very "green" while the "mountainous" countries are very "brown", but that may just be me. There's still a couple I'm not entirely sure about - Jamaica's not really Central America (I was going to go with Anglophone North America and Hispanophone North America, but freaking Montreal had to exist and there are parts of the US where Spanish is dominant, and I wanted to keep countries together because casual viewers are more likely to remember, like, that the cheese wheel task happened in Switzerland than they are to remember it was in TAR14) while the Philippines isn't really the same sort of location as the other Pacific Islands - but by and large I'm happy with this list. If there's any improvements anyone can make, feel free to reply.