Is nanite transmitter complex (level 3 artifact, 4 charges) supposed to be an upgrade or a project? Currently it is impossible to build it since it is neither, it seems, and just sits there in the list.

In ArtifactImprovementDefs, it is configured as:

<ImprovementType>Special</ImprovementType>

<PlacementType>Special</PlacementType>

Nanite transmitter center (level 2, 2 charges, upgrade building):

<ImprovementType>Special</ImprovementType>

Study motivational helix (level 3, 4 charges, project):

<ImprovementType>DurationalProject</ImprovementType>

<PlacementType>Special</PlacementType>