As I said just use the construct 2 split image tool.
1. Right click on the animFrame list > Import sprite strip
2. Set the number of cols and rows
3. Click ok
and you're done.
So yes that only works with same sizes as it's basically a grid based puzzle.
Also be carefull to put the hotspot at top left for the tiles and the background image (which is also used for rows and cols calculation for the winning condition, so be carefull)