I did some testing today and noticed a few things:

If you import a business using the Automated Lead Importer and you edit the listing via the front end:

If you click 'update' you will lose the Google reviews:

In the back end, at first gland it appears there is a section to update the reviews & ratings:

If you click update, the listing is re-imported from scratch, you lose all edits to that listing (photos, name corrections, categories, phone number etc)

In my case for some of the listings I had auto imported the categories from the GMB listings, I had since removed the nonsense categories completely from the backend (point of interest, store, food etc), when I updated the listing, all those categories were recreated again.

What is the intended function of 'update' in the automated lead importer section? I would assume that if you help a business start getting great reviews, you want to be able to import some of those new reviews to be showcased? Why would someone want to lose all the other edits to the listing?

There are two other references I see in the feature request posts that are related: