A thought: you could 'solve' the separator problem by providing a box where the user can choose whatever separator is appropriate. It would default to comma, which would cover (I think) the majority of uses. Something like the following:
The user (me) would change it if values contain commas, which can happen for authors-like columns and single-value columns like publisher, series, enums, and non-tags text.
On the other hand, having a choice means one must understand when to choose. Maybe it is better to have a rule, not a choice.
