In the JSON generator, it assumes the Western convention of forename surname. This is a format not specified by GEDCOM, which instead says (in GEDCOM 5.5.5) that:

The surname of an individual, if known, is enclosed between two slash (/) characters. The order of the name parts should be the order that the person would, by custom of their culture,have used when giving it to a recorder.

Examples

William Lee /Parry/ - given name William Lee, surname Parry
William Lee - given name only or surname not known
/Parry/ - surname only
William Lee /Mac Parry/ - both Mac and Parry are part of the surname Mac Parry
William /Parry/ Boatsman - surname Parry embedded in the name string
William Lee /Pa.../ - surname partly unknown (unreadable)

In the current behaviour, any text after the surname is discarded. This is a bug.

The current implementation is the following:

function extractName(name: string): { firstName?: string; lastName?: string } {
  const matches = name.match(/\/([^\/]+)\//);
  if (matches) {
    const lastName = matches[1].trim();
    // Replace the last name part (including slashes) and trim the result
    let firstName = name.replace(matches[0], '').trim();
    // Replace any occurrence of double spaces with a single space
    firstName = firstName.replace(/\s\s+/g, ' ');
    return { 
      firstName: firstName || undefined, 
      lastName: lastName 
    };
  } else {
    // If no last name is found, just return the trimmed and cleaned firstName
    return { firstName: name.trim().replace(/\s\s+/g, ' ') };
  }
}

Which results in:

extractName("William Lee /Mac Pa.../ Boatsman")
// {"firstName": "William Lee Boatsman", "lastName": "Mac Pa..."}

This way at least, no information is lost (even if it may not be presented in the desired order on topola).