A spreadsheet that size usually started as a simple tracker and grew into the place where inspection scope, schedules, results and follow ups all live, which is why it is so hard to replace and so easy to break. Nobody in the field can use it, so results get written down elsewhere and typed in later.
The way out is to split what the spreadsheet is doing into its parts: the list of what needs inspecting, the checklist for each inspection, the schedule and the record of results. Each of those becomes part of a workflow where inspectors get their assigned inspections on a device, fill in the checklist at the equipment and the results update the record straight away. Interface runs inspections alongside procedures for this reason, so the field work and the record are the same thing.