The current History structure should get built/rebuilt as you use the device. Not sure how migration might be working, for the changes made to how History data is maintained.
KOReader's Stardict dictionaries are not the same as those for the Kobo software. If you check in "Dictionary settings >" you will find a number of options including a "Installed dictionaries", that will show the dictionaries detected (in the proper folder) and those installed and usable.
Luck;
Ken