Dragging and Dropping does did not work.
With that minor edit, you got that last right!
I have no idea what you did, or why it failed but obviously it did fail. My suggestion is to start over and this time, do it Apple's way.
- DO NOT MOVE ANYTHING VIA DRAG AND DROP
- Disconnect the Time Machine drive from your old computer
- Connect the Time Machine drive to your new computer
- Follow these instructions to boot your new Mac into the Recovery Drive mode
- From the Utilities menu on the Recovery Drive launch Disk Utility
- Select Macintosh HD (the Volume not the Drive itself
- On the Disk Utility menu select Erase
- Choose GUID partition scheme and APFS as the format
- Click Erase
- Quit Disk Utility
- Launch Install macOS and follow the instructions until it asks if you want to recover from a Time Machine backup
- Choose the Time Machine drive
- Choose all the restore options
- Go watch a good movie on TV for a few (2 or 3) hours
- When the installer and Migration Assistant have completed, your system will reboot from Macintosh HD and all of your and your wife's data files will have been restored.
- Log onto your account and trash the "Recovered files"folder on your desktop, if it exists.
- Launch System Settings > Time Machine and choose the Time Machine Drive
- When asked if you want to assign the Time Machine backups on the drive to the new computer, answer in the affirmative.
- Enjoy your new iMac.
