You may need to load the same values that Structure shows on the Structure Board, especially if it's a total value, progress value or other Structure-specific value. This is done via StructureAttributeService.
About Attributes
One of the core concepts in Structure is the Attribute abstraction. An attribute is something that can provide a value of specific type and meaning for any row in a forest.
For example, a "Summary" attribute would produce the value of Summary field for issues, the name of a folder for folders and a person's full name for users. Some attributes may be applicable only to certain item types and would provide empty value for all other items.
Besides item-based attributes, which provide values that depend only on the item in the forest, there are forest-based attributes, which are calculated based on the whole forest and items in it.
Forests and Attributes are two main concepts that make up the Structure grid. Looking at the Structure Board, you see Forest in the vertical direction – rows and hierarchy are taken from Forest, and you see Attributes in the horizontal direction – all columns load Attributes from the server and display those values.
General Approach to Loading Values
Let's assume that, after Reading Structure Content, you have StructureComponents instance and an instance of ForestSpec for a forest. We can read a number of attributes for a number of rows by going to StructureAttributeService.