Speaking as an American Motorcyclist. With an American motorcyclists point of view. The question of how would the Thunderbird sell here ? How would the cruiser market people receive it here?........ Not well IMHO. Especially with it's small displacement for a cruiser.
It may have some interest as a "beginners" bike for those who want a larger cruiser ? But.... the Harley draw is huge here, and they now have a "beginners" bike. Harley's Marketing and Mystic is enormous here. I have a feeling.... because of the Thunderbirds styling, like many other "clones", it would be shunned here by many in the cruiser crowd. Many.... not all...people who buy Clones here, Wind up selling their Clones to get the "real" thing, through marketing, peer pressure , hype or whatever. AND , the small displacement Clone cruiser market is not big here to begin with.
Americans who go to brands like RE, Triumph, Ducati, Moto Guzzi, Ural, and etc. Are generally looking for something different, and certainly not a Clone of what they don't want... for the most part I would think.
But, with all that said. America is a big place and I think they would sell some of them. Some Enfield enthusiasts ?.... People who like the idea of having something different perhaps? Like us !
And not a perfect comparison now, but I don't think Triumph sells a huge amount of Bonneville America's here? A better analogy may be...... Trying to sell Pizza Hut or Domino's Pizza in Italy ?.... Juuuust not quite right some how ? Keep it REal.......