the Quote you are referring to is the 1st try to link a complete topic using the "Link to external Help" and selecting a topic in the remote project.
This did not work when generating ewriter help. when reading the forum I understood this and tried the snippet road.
I included the snippet in the way you described but I did get the text but not the images.
In that old H&M 6 topic there was no mentioning of including the path as you describe here.
If it is from an external snippet file or another project then you need to add the folder containing the referenced images to the search path of the project where you are inserting the snippet (Configuration > Common Properties > Project Search Path).
I will try again but I still would like the feature to be able to include complete topics for all kinds of output as picking a topic from the shelf is i.m.h.o easier that for each topic to pick the text as a snippet and fixing the path in each project.