Normally, you would not use Disk Utility with a Time Capsule at all.
In general, to check the integrity of your backup file(s) you would hold down the option key on your Mac while clicking on the Time Machine "clock" icon at the top of your Mac's screen.......and then select Verify Backups.
This is a process that checks to make sure that any files have not become corrupted. If a problem is detected, Verify Backups attempts to repair the files.
If you try this and the Verify Backups process cannot run, then the backup files were likely damaged previously. Nothing else to do at this point other than erase the Time Capsule disk and start over again with new backups of each Mac on the network.