I agree there is some inconsistency.
Could you do the following, to see better, what is going on here:
- add the <export-vtk…> tag in your precice-config
- load the .vtk files into e.g. paraview and apply a glyph filter.
As a result, you can see the data precice gets form each participant and which data points are used during simulation.
precice doesn’t care, where your data locations are derived from i.e. faces or nodes. Values are just mapped conservative or consistent depending on your config.