I don’t know if and how these missions in question were remade for Reforged, however they were not specifically created for the new version of the game either. It’s realistic to expect you had to start from somewhere before adding voice files and other languages to them. You didn’t make them from scratch in the last two years during the creation of the new game.
By default in the final version of the game that shipped two decades ago had only three missions.
- Introduction: [The Prophecy]
- Cinematic: [Thrall’s Vision]
- Chapter One: [Chasing Visions]
- Chapter Two: [Departures]
The other missions were cut out of the full game with just the tutorial levels left in WC3:ROC. They were first seen in the WC3:Demo which was made available after the release of the game. In WC3:TFT the company made a custom campaign which included the missions that were exclusive to the demo campaign; however, the voice acting was removed as the demo voice acting had only been recorded in English and Blizzard was unable to localise it for other regions.
- Chapter One: [Riders on the Storm]
- Chapter Two: [The Fires Down Below]
- Chapter Three: [Countdown to Extinction]
At some point or another while TFT was still getting patches, these three missions got removed from the game files with one of the updates. The thing is, these maps exist somewhere, either on your servers or one of the fansites. The missions in question are designed specifically for the Classic game and despite the lack of voice acting and other minor details, they are entirely scripted with many trigger systems and they play out with almost no bugs.
You could very easily find those maps online and include them in the Classic version just to make it a more complete experience for the players that remember them, but are stuck with the old game key. It would mean a lot to those players and it wouldn’t need a lot of work. It is currently impossible to do this ourselves as the custom campaign system is not included in the new client.