Yes, you're right. We recommend to use 560 ohms resistors in the Guard and shield lines as mentioned in our MBR3 design guide.
In the MBR3 kit, you can find that the guard sensor pin (CS2/ GUARD) has a 560 ohm resistor. In the kit we use jumpers (A,B,C) to select the different features (any two from liquid tolerance, Buzzer and HI). Since the HI and shield pin are multiplexed in the pin#9 (CS15/SH/HI), we didn't use the 560 ohms resistor there.