The official CSV file contains comment in parentheses. Why not using a dedicated field per row for it?

If the line is longer, then the text is split to multiple line. The postcode, names are repeated.

issues. There are catch-all postal codes for many areas, where the neighborhood is given as "except the following", and the only thing to do is look for that exact string and exclude it.

The separate romaji file is of low quality.

That's why posuto aims to simplify this.