There is no way this could work. The EDA tool (e.g. KiCAD) is only the first step of the fabrication process - you generate Gerbers from your KiCAD board layout

There is no way this could work. The EDA tool (e.g. KiCAD) is only the first step of the fabrication process - you generate Gerbers from your KiCAD board layout, which are a highly standardized format that can be viewed in a variety of independent pieces of software. There are also multiple stages of design validation - both in the design phase, and then in the physical phase of actually inspecting your fabricated boards. The chances of any "malicious" circuitry slipping in are next to nil.