In my experience the phase "reproducing action", as seen in several
Stecks that I have come across, means what we call now "half Duo-Art".
I don't think this dubious product was available in America, and
most people I know think it should not have been available anywhere!
It certainly is not "Duo-Art" and is more akin to an expression piano
where some of the expression is put in by the player-pianist.

Paul Morris