Do you mean wallet developer or user?
I mean user. For example, typos like 'Addres' would mean labels are skipped on import, which might be difficult to detect in a file with many labels. Of course the wallet could try to determine what the user meant from the reference itself, but then we are back at square one (and some implementations might not do this).
That's good point. As power user, i expect wallet would shows warning message when it detect row with invalid data. But i also know some developer chose to hide the message on log file to prevent scaring user or don't bother implement it.