Suggest to find the root cause. Please double-check Cmod, Rb, Series resistors on sensors are in recommended arrangement, double-check VDD voltage waveform and XRES waveform are stable.
The Debounce parameter in CSD is used for finger touch report, not for negative spike.
Recommend to disable sensor-autoreset, increase Low Baseline Reset to 100, 150, 200, 255 step by step to verify if it can work.
In addition, you can add IIR filter manually to filter the spike.
At last, recommend to migrate your design to PSoC4. PSoC4 CapSense is more flexible and easier to tune. The performance will be better either.