Hey @mlnrt ,
unfortunate to hear you are often puzzled by our API.
Happy to hear more about other cases which puzzled you on exploring the library.
I expect the gds.beta.graph.relationships.toUndirected to do exactly what you want.
Reading GDS Import/Export of UNDIRECTED Graph I understand your confusion though. You would like to avoid have the undirected relationships to be written back as undirected relationships. This sounds like an interesting feature to me and I will propose it internally to offer such an option.
As a workaround, I would advice to use the cypher projection (or cypher aggregation) + gds.beta.graph.relationships.toUndirected. Then you have two relationship types one directed and another undirected.
For the export, you would only like to export the directed relationships.
So i would advise to first drop the temporary relationship type created by toUndirected using gds.graph.relationships.drop before exporting your graph.