Typically, anything released by Kato JP, gets released by Kato USA 2-6months afterwords, if it is a universal item such as the Unitram/Portram and building.
The same is typically true for the UK, but since there is no real Kato UK, it is all imported by M.G. Sharp Models, and most sellers on eBay usually import their stuff from the Japanese sellers on eBay at a marked up price. including BT Trains here in the US.
The number one delay in the releases believe it or not is due to the translation of the product materials from manual to the boxes.