I've been going back to some research I did quite a while ago, before 8.00 appeared. On opening with 8.08, TMG does a conversion to the new format, and everything works properly, EXCEPT that the "Add Person" box has incorrect labels for the place name boxes. This is not really a problem if you are a regular user, because you fill in the boxes in the same places as usual, ignoring the labels (which are associated with names rather than places). Occasionally you need to tidy up the Master Style list for places, too.
I've come up with the following work-around:
1. Create a new project.
2. Cancel the wizard which adds the first person. You are left with an empty project.
3. Use "Add Person" to create a test person. The place name fields ought to be labelled correctly in TMG8 style.
4. Use Dataset Manager to rename the dataset so that you can recognise it later.
5. Use File, Merge Projects to merge your real data to this working one.
6. Use Dataset Manager to merge the newly imported data to your nearly empty dataset.
7. Use Dataset Manager to delete the imported dataset (usually number 2), leaving the one with the name from step 4.
8. Start to add an unrelated person to ensure things are still showing properly.
At this point you have a copy of your project with things sorted out. Check that it looks decent.
9. Delete the test person from step 3.
10. You can then use File, Copy Project to overwrite to original one, so that the name is correct again, should you desire.