From the article > The presumed software release timespan (at least 33 months between August 1986 > and May 1989) is particularly odd considering this is an extremely rare and > unknown system.

I wonder if there is a connection to Japan's FGCS project which was active during that time frame. https://en.wikipedia.org/wiki/Fifth_Generation_Computer_Syst...

It would make sense if Sega was involved and the activity on this "extremely rare and unknown system" was due to it being funded by research grants instead of purely commercial new product development. The FGCS was heavily invested in advancing Prolog based systems and that makes the possibility of a connection to this system even stronger.