The are a couple of ways that MaxError could be set to 25%. 

First, MaxError increments 1% for every 4 cycle counts without a learning cycle.  A learning cycle involves discharging the battery down to 7% RSOC. The gauge makes an FCC correction here and will set the MaxError back to 2%.  If your application does not allow the battery to discharge down to 7% every once in awhile, then MaxError will increase.

The second way MaxError can be set to 25% is on a voltage correction, as you stated in point 2).  After a reset or loss of power, the gauge, upon power up, will set the RSOC to 25%, 50%, or 75%, depending on the Voltage. The VOC25, VOC50, and VOC75 thresholds determine what voltage corresponds to each percentage. After a learning cycle (discharging down to 7%), the gauge will learn a new FCC and the MaxError will drop to 2%.