Transplanting non-FR settings
1) Ravenloft (original boxed-set).
2) Temple of Elemental Evil.
No, these are not set in the Forgotten Realms, but that's never stopped me from plunking adventures from other settings into the vast wilderness areas of Faerun.
Ravenloft was designed to emulate the feel of medieval eastern Europe. Placing the adventure in the mountains to the north-east of Rasheman, which has some of the same ambience as the culture of the Ravenloft adventure, and proximate to the Hordelands farther east, worked for my players. As the DM, you can chose to make it an actual part of Faerun or simply a portal access to the world of Ravenloft. I chose to make it an actual location. Its boundary was, for most folks, a point-of-no-return. As I didn't want the PCs to be trapped there for the rest of their mortal lives, I developed a challenging-to-achieve way out.
Translating the Temple of Elemental Evil to Faerun took a bit more work. A lot of that adventure was particular to locations in the World of Greyhawk. Instead, I decided to plop it down in the jungles of Chult. The heat and humidity there seem to me to be an appealing climate for Zuggtmoy (or Tsuggtmoy), the Demon Queen of Fungi.
Among other things, this meant the PCs had to contend with several cultures they had little-to-no previous knowledge of and they were introduced to the dinosaurs that still live in the interior of Chult.
Consider Chult for your next vacation. Come for the sun, stay for the mold and the common bugs as big as stirges - or stay for the Raptor's Lunch: you might get to be the special of the day!