I don’t get an error message, but the bookmarks never appear. I have had this problem for as long as I started using Brave. this problem has persisted since I started using Brave and earlier versions of Safari.
also, I doubt I have ever managed to import passwords from Safari into Brave. (not absolutely sure about this as I use Brave most of the time.)
currently using Brave 0.60.45 Chromium: 72.0.3626.109 (Official Build) (64-bit).