There is a lack of consistency here
Presuming that by “presence in the real world” you are referring to the quantity of vehicles that have been produced, I don’t think your logic really checks when you look at all the other prototypes that Japan and many other nations contain throughout their trees.
The Chi-Ha LG, for example, is another gimmicky vehicle that “exists” only as a single low quality piece of footage showing one angle of the vehicle, with literally nothing else known about its history or functionality. Or perhaps the Chi-Ri, which while having multiple photographs and documents surviving postwar, is an incomplete prototype lacking its main gun with another gimmicky feature found on very few other WW2 tanks; that being its unique autoloader.
I hardly see the issue with their playable nature if we can prove they existed, which the O-I most certainly did regardless of if the “only photo evidence is trustworthy” gang says otherwise.
