The review screen shows you every single row that's about to be imported, with a clear indicator of which ones look good and which need attention. The table keeps the fields you change most — category, tags and recurring status — right in the row, and each row has a side panel for everything else. Take the time to fix or simply uncheck anything problematic — since importing is all-or-nothing, even one row with an issue will stop the whole batch from going through.
Not sure why a row looks the way it does? Use View original row to open that exact line from your file in a drawer next to the column titles, with each column labelled by the field it fed. An icon on every row shows whether it is an income or an expense, and whether it passed its checks.
Rows that already exist in your ledger — same account, day, amount and type — get a warning icon in the Type & check column (hover it to see the matching transaction and its status) and start unselected. You can still select one if you really want a second copy; the review then tells you how many selected rows already exist and offers to unselect them.
If your file had lines that could not be read as a transaction at all, a notice tells you how many were skipped, so you know nothing disappeared silently.