The Soviets (at the time) didn't "copy" it. They stole the plans and made it from them, adding in a few alterations, although the plans they stole were purposefully flawed.
If you're up for it, you can visit the Buran's in their final resting place in Baikonur. They're just sitting there rotting away. Here's a video of some kids who broke in and had some fun exploring: https://www.youtube.com/watch?v=-q7ZVXOU3kM
Article about the Soviet's espionage to get the plans: https://www.19fortyfive.com/2021/12/buran-how-russia-stole-t...
The US Space Shuttle was the (heavy) inspiration, but the Soviets put their own spin on it.
My point is that they aren't capabilities, just specifications and promises for a cutting edge, developmental technology.
[1] https://en.wikipedia.org/wiki/Space_Shuttle_design_process