Reviewing activity and hours

I’ve used many systems, and Nozbe is great for tracking activities in a fast moving environment.
The one thing I’m having trouble with is how to see past activity and time spent on those activities. I like to review the past activities accomplished by project in order to improve effectiveness. I enter the time it takes to complete items and would like to review “the past week or month” for example to see how well things were done. There also seems to be a time period when a completed action item doesn’t show up in the current action items for a project and it also doesn’t shoe up in the completed action items.

Is there any way to look back at completed items by project and see total hours?

I’ve exported the backup to the text file. Is there a way to format an excel file to take the backup and review, sort, and total the data?
Thanks