We are usually not afraid of 'invented' retro. Nothing wrong with a Kawa 800 cc twin. But a half grown Indian clone from the States is not our taste. Real retro bicycles are of course not conceived as retro. They are just living fossils. The manufacturers have generally made the transition to the present with limited resources. And when viewed with the right approach, they give the best of both worlds: the old school looks plus an at least acceptable degree of daily use.
Harley's Big Twins are not retro bikes. Those are just hugely modern engines whose historic looks are cherished.
For the extremes of integrity, brands such as Enfield and Ural go. They make motorcycles there as intended. And that such a machine now has a disc brake, a starter motor or a cat somewhere? Not bad: the basis remains classic enough.
We recently drove a new Ural and a very fresh Enfield. They lack the patina of the years. But what are the great machines!