Use this 3 files for debranding:

MAIN: W595_R3DA026_MAIN_GENERIC_LD_RED52
FS: W595_R3DA026_FS_CENTRAL-EUROPE_RED52 and
CUSTPACK: K850i_1201-0116_R11A_GENERIC_CENTRAL-EUROPE (YES you can use this custpack for K850 in your phone)