Short answer: pick the delimiter the file uses, pick the one you need, and the fields are re-joined with quotes where they are required — nothing else is touched.
The three cases that break naive converters
- Decimal commas. 1299,50 in a comma file splits into two columns. Use semicolons.
- Quoted delimiters. A name like "Rao, K" must stay one field; the parser respects the quotes and the writer restores them only when needed.
- Newlines inside a field. Legal when quoted, and the reason a row count is not a line count.
When it is not just a delimiter problem
If the columns are shifted, the file may contain an unclosed quote — the notes say when rows have different field counts. Moving to a structure instead of a table? TheJSON ↔ CSV converter is the right tool.