I think the problem could be that you use findAll to get a single record.
The data object expected from findAll should be an array, but in the response code you are showing i see a single record.
Try using something like this.get('store').findRecord('auditTrail', 41, {include: 'audit-trailable'} )
Edit
The template you mentioned is a route template or a component template? If it is a route template probably you only need to change it like {{model.eventName}}