Tomica World Station

駅・ホーム (1979-1987) is the roots of ゆめがおか駅. Don't you feel that these 2 stations look similar?
こうか駅 was actually manufactured in 1985-1993 as a single item with the J-22 number, the same time as J-16 ブロックビル.
This is actually J-22 although it is not as visible. Please pay special attention to Block Building.
Also note the ST mark on both the old header of Block Building and new header of Yumegaoka Station, you are actually questioning one of the biggest mysteries of Plarail: "When was the new header released? It seems that the old header and the new header had a generation overlap.". It is known that the old header lasted until 1987 before the new header was released in 1988. This goes back to questioning why the Furano Express set is using the old logo when it was manufactured during 1988, the new logo era.



Also, the Furano Express Set (1988) and the mysterious Sotetsu 300 Series Shinkansen Set (1991) has the Yumegaoka Station.



The point of it being "Elevated station" is because you can fit the station on top of the block building. This explains why Yumegaoka Station and Block Building were released at the same time.



I hope I answered the Japanese side of the story. You can proceed from here I suppose.