I am familiar with them. It employed a somewhat different method of transmitting vibrations from the voice coil to the diaphragm, more akin to the standard pistonic approach. Additionally, that diaphragm was not honeycomb but featured a radial and star-like core. The aluminium foil skin prevented the internal cells from functioning as an orchestra. Production was halted by the Japanese and Philips, all at once by the end of the 1980s. In the USSR, Estonia and Leningrad continued to produce those until the 1990s. Later, they maintained production for a while in St. Petersburg (formerly Leningrad) until the company eventually went bankrupt. Both Philips, the Estonians, and the Russians produced honeycomb panels.
Accuton also employs pistonic motion to drive the convex honeycomb diaphragms, thus still utilising the old technology to some extent. However, they tend not to discuss in detail how the convex honeycomb diaphragm actually functions. One could say, new-old technology. Estalon uses Accuton drivers, and the creator of Estalon is from Estonia and had worked at RET, if I am not mistaken.
This Ukrainian engineer, Oleh Lizohoub, employs somewhat
newer technology, which is why I referred to it as revolutionary. There are three different actions occurring simultaneously on his flat composite panel. By the way, balsa is porous and has a honeycomb structure.