Yes, that is really a mess! Or nicely stacked, as juiceme would say.
You somehow managed to shift roots and home from p2/3 to p3/4. Your approach above editing ubiboot.conf may work (for sure this is the reason why kernels are not found), as it searches on harmattan rootfs (i.e. /dev/mmcblk0p2) boot folder. But due to your partition layout they reside on /dev/mmcblk0p4. I suggest you do a reflash --no-preserve and start all over. But before you should try editing ubiboot.conf as stated above. And you will end up with a system having the home partition not mounted (would need editing at least /etc/fstab). Juiceme may tell more here.