Hi Robert,
Thanks for the feedback.
This is absolutely the kind of problem that we want LogViewPlus to solve. Unfortunately, reporting is an area of LogViewPlus that is still in the rudimentary stages. We have plans to rewrite this feature over the next 12 months, but for this issue I think we should focus on getting the data into Excel.
LogViewPlus has a special 'Elapsed' column:

This column contains a calculated value of the difference between the given log entry and the log entry preceding it
in the grid view. So, if you were able to create filters to isolate the start and end events and then merge those two filters, this column might contain the data you need. This approach does assume a synchronous processing of events as the relationship between start and end is assumed. It also requires that there are no additional log entries between 'start' and 'end'.
That should allow you to 'see' the data, but exporting it to CSV is a bit of an problem at the moment. This is an oversight. Fortunately, we have a BETA release planned for today. I will add the ability to export the Elapsed data if the column is visible.
Once the
CSV export feature is working correctly, you could consider setting up a
Report Command.
Hope that helps,
Toby