Hello @guilopec, this is definitely something we have seen a few users ask about. That documentation you have for CloudTrail is the best resource I have found with information on using it for Quick Sight assets. As for the CloudWatch logs, I am curious as to why only 15 dashboards would be appearing. Is there any chance that those have these options selected in the share dashboard console and the others don’t?
Also, this is a bit of an older topic, but there was some information shared here about some of the ways other users have tried to get more information about dashboard usage.
There still is not a ton of out-of-the-box functionality available for tracking user activities in Quick Sight, but I hope this helps!