I appreciate the information provided, I understand you are occasionally experiencing filesystem corruption within some of your GLK19264-7T-1U units. There are two ways of locking down the filesystem to prevent unintended changes which you may want to explore.
The first is a software lock using the Set and Save Data Lock function detailed in your manual
; the filesystem lock is level 5.
The second is a hardware lock, which will require that a 0 ohm resistor or jumper be placed on two pads near the 8 pin external EEPROM located using page 7 of your manual.
If you have any questions regarding either method please don't hesitate to ask.