Yes, you can generate reports that will be grouped not only by sprints, but also, it’s possible to get reports by component, epic, label, project, etc. You can do it by switching to ‘Group’ tab and choosing which criteria to group the report by.
Will worklogs from Tempo visible in ActivityTimeline?
For Server: all the worklogs logged through Tempo Timesheets or any other time tracking application will be visible in ActivityTimeline by default.
For Cloud: You need to generate Tempo API token and insert it into ActivityTimeline Configuration->Tempo integration tab in order to enable synchronization of worklogs from Tempo Timesheets to ActivityTimeline.
In Track module of ActivityTimeline reports are generated on team basis, so if you would like to see the detailed information on person basis, you need to group the data by Users. For this go to 'Group' tab and choose grouping by person:
How can I get a report for issues related to a specific custom field, i.e. Customer, Account, etc?
In case you have some custom field that groups Jira issues by some criteria (i.e. Customer) and you would like to get a report of all worklogs that are related to this custom field, you can generate Timesheet Report based on the Jira Saved Filter (JQL), that would look similarly to: customer = Customer A and then simply generate a Timesheet in ActivityTimeline based on this filter, which can later be exported into Excel format.