Merge attributes filling empty cell

Might need a screenshot out of Data Inspector for one of the Output features that is causing difficulty @aron? I'm not sure how you would end up with an output matrix like that for a single attribute comparison of one set of feature vs another. You might get multiple List items, but each List Item will retain the original Attribute Names and values

If the problem is similar to the previous post, then it sounded like you have attribute B.RoadAttribute you want to merge onto A.RoadAttribute, for the line segment components of A and B that overlay each other.

IF you don't want to split the Geometry of the features of B and want to leave them intact (but in your original post using Intersector this was similarly splitting the original feature lines in B), then hollyatsafe's answer can be used for SpatialRelator, although for roads you would use a Spatial Predicate of 'Requestor Overlaps Supply' instead of intersects, however a List again would be needed on the output if there were multiple lines with different values from A overlapping a single feature from B, and you needed to process and resolve these.

Sample workflow as below for where there is only one available value from A. There is another Port there in the TestFilter for where there are multiple overlapping segments from A (apologies mixed up the names for A and B in the late stage of the workflow, I should have called it AttributeValueFromA), to use whatever logic is needed to resolve those like giving priority to one value or another y using a ListSorter or ListExploder+Sorter etc.

The final step from ListSearcher simply finds the first AttributeValueFromA that has a non-Empty value (A Regular Expression = ".") and puts this value in a new Attribute which can be compared to the original Attribute in B, and the value in B can then be overwritten with a further AttributeCreator step.