Addon “PlaceTool” from Kari Kujansuu simplifies place hierarchy import process. Import in Name and Title fields full hierarchy of a place and PlaceTool is able to generate the hierarchy after the csv file is imported to Gramps. The tool can resolve a hierarchy in ordinary or reversed order. You can also add a surrounding place to multi selected places in one sweep (or delete before that surrounding relation of all selected places.
I use PlaceTool all time in Isotammi project and warmly second it ! Thanks Kari, father of SuperTool also.
a practical hint: full hierarchy needed means only that known parts of hierarchy are in descending or ascending order and separated by comma or blank. So “Helsinki”, "Helsinki, Finland, “Helsinki Finland” and “Finland Helsinki Töölö” are all valid to be processed by PlaceTool. Afterwards is easy in Gramps to merge all Helsinkis to one “Helsinki, Finland”.
So do not unneeded standardize place hierarchies before import.