The "liquid system" is just very simplistic particle system, quite often it shoots in completely random direction, does not collide with anything, and looks really bad in general.Is that liquid system with cum inflation they were talking about in yet?
The inflation happens, but you have to probably "play" the game for hours to actually see the effect. I saw it only on screenshots, the bulge shapekey also looks pretty bad, for some reason it's more around the upper belly/ribcage.
Both look like some proof of concept hack that should not take more than a day to implement for anyone semi-competent. So it probably took them months.