The bg_province.xcf file in the gfx/interface folder is corrupt and thus does not extract.
I am still concerned about the size difference in the files as well.
Imperium 1.2b includes the maps folder which has two files in it, map.bin and tree.bin, that, combined, account for 43.6mb of the total Imperium1.2.rar file size.
I do not know why the maps folder was included...
I'm going back to isolation in a few hours (no internet, no games... ).
Dont worry, he's still alive and still thinking about modding.