Writing to serial LCD seems to interfere with servos
You are using SoftwareSerial which turns interrupts off when sending/receiving in order to precisely time gaps between bits. The Servo library may use hardware timers, but to work on pins 12 and 13 would require interrupts to "copy" the pulses to those pins. Thus the copies will be distorted when writing to, or reading from, SoftwareSerial.

I suggest using hardware serial (pins 0 and 1) for talking to the LCDs, which does not turn interrupts off. Alternatively, implement the servo positioning using the hardware timers yourself, which (once set up) won't change the pulse widths if interrupts are turned off.