2 things. One, why does the system data matter? There's almost nothing in common between 4.4.2 AOSP and 4.2.2 LG UI, and anything useful is already synced via Google. Second, that's a big negative even if you wanted to. Unless you want to bootloop like a pro, do NOT restore system data on a different Android API version. It's a bad idea normally but especially here. I personally use TB and just restore user apps + data.
Phone: Sprint LG G2 "LS980" ROM: CarbonROM 4.4.2
Tablet: Amazon Kindle Fire (Gen 1) "otter" ROM: HellKat 4.4.2
Tablet: Google Nexus 10 "manta" ROM: Purity ROM 4.4.2 Kernel: KTManta
Retired: Motorola Photon 4G.......Never again Motorola.....