Well, I don't know on what devices you were using TWRP, I also sometime had issue with restoring with TWRP, but most of the time it was perfect. I could restore or System + Data or just Data, and it was very useful for clean installation, I had just to wipe everything, install the new ROM, and restore all data like a charm. on Mi 1, Mi 2, M2s, Mi Note, Mi Pad, Mi 4 S, Mi 5S, Mi Note3, Mi 6, Mi 9SE, and now Mi 9 Pro who doesn't have yet official TWRP.