The number of people who know Wen Yan fell into the Netherworld isn't particularly large, but if you count it up, it's actually not that few either.
Most of the people handling things inside the Scorching Sun Department only know there's some operation targeting the Netherworld. As for the specifics, very few people are aware.
According to internal rules in the Scorching Sun Department, a lot of things are split up and carried out piecemeal.
It's like building a piece of equipment—each person is only handed a single part, with no context, just a set of required parameters. Even those making it by hand have no idea what it's for, and, frankly, anyone with half a brain doesn't want to know either.
As for whether giving the required specs could lead someone to reverse engineer the whole picture, it's not just individuals—even the factory itself may not really know what their parts are used for.
