How I would handle this.
Adjust Qualified Immunity for police to more closely resemble the version used for other first-responders. If the officer acted within the bounds of their training and professional standards they have immunity, if they did not, they automatically lose that immunity. All costs related to determining whether or not immunity applies in any given case are born by the state or federal government. This determination is to be made by a qualified review panel as determined by the local jurisdiction and their decisions are considered legally binding.
If a given department fails to implement proper training to meet professional standards they become fully liable for the consequences of said deficiency, not the individual officers.
If a situation arises where, operating within the bounds of training and professional standards, an officer nevertheless manages to violate constitutional protections in an unanticipated manner, then the officer is still protected, but the department is liable for nominal damages so long as training and professional standards are updated in a timely manner in response to the unanticipated issue. However if it is shown that the department was aware of the potential constitutional violation yet failed to update their training and professional standards, then the department is fully liable for full civil damages and will be required to immediately update their training and professional standards.