It turns out that the "fsg" and the "backup" partitions are meant to take copies of the modemst1 and modemst2 partitions - this can be done/forced by executing "reboot nvbackup" in terminal or with adb. So these partitions are meant to hold the backups of modemst1 and modemst2.
Changes:
Added: Stock Graphics Driver (4.4.3). (Thanks knizmi)