1. Try adding the options "alt_touchpad_config" / "alt_touchpad_config2" and see if it fixes your issue.

2. Check if your touchpad driver is correctly detected or not by installing crouton ("easy way" configuration) and see if the touchpad works there or not.

If it does not work, you can create an issue, else continue reading.

3. If your touchpad works in crouton but not in chromeos, it is due to a specific configuration needed by the cmt driver used in chromeos.

In that case, you can try to modify the first section of the file /etc/gesture/40-touchpad-cmt.conf to better manage your touchpad using other options found in that same file or the ones available at:
https://github.com/hugegreenbug/xf86-input-cmt/tree/master/xorg-conf

If you find a config that works and you want it to be present in brunch as an option, do not hesitate to create an issue with the related config.

4. I tried many configs but nothing worked.

Unfortunately, there is not much I can do in that case as I do not have access to the related hardware.