This warning indicates that the balanced partitioning strategy of the fitter is turned off in order to find a successful fit for the design.
Balanced partitioning is a method to keep the CPLD utilization uniform across the device. Therefore, if the fitter successfully fits the design, the user can ignore the warning as it is only a strategy for partitioning. If not, the user can try to reduce Max_Fanin, Max_Pterm_collapse or change Clock_enable_optimization strategy settings within Optimization Constraint Editor.