@Nicolas
The Import plugin already alters some the records hashes and adds custom field for later use, they're all using the _imported_
namespace.
{
"tid": 29897,
"uid": 8,
"cid": 2,
"mainPid": 29897,
"title": "A quaint old forum tradition: The Introduction",
"slug": "29897/a-quaint-old-forum-tradition-the-introduction",
"timestamp": 1414978528000,
"lastposttime": 1415421136000,
"postcount": 41,
"viewcount": 9,
"locked": false,
"deleted": false,
"pinned": false,
"_imported_tid": 29887,
"_imported_uid": 16165,
"_imported_cid": 1,
"_imported_slug": "",
"_imported_path": "/Forum/207593/message/1414978528/A+quaint+old+forum+tradition-+The+Introduction%26gt%3B%26gt%3B%26gt%3B",
"_imported_title": "A quaint old forum tradition: The Introduction>>>",
"_imported_content": "",
"_imported_guest": "",
"_imported_ip": "96.232.167.174",
"_imported_user_slug": "",
"_imported_user_path": "",
"_imported_category_path": "",
"_imported_category_slug": "",
"relativeTime": "2014-11-03T01:35:28.000Z",
...
check this thread to find out why.
nodebb-plugin-import-network54/issues/2 and how you can delete them if you choose to, the importer does not force you to delete them.
If you want to add more fields, I am more than happy to accept a pull request or to add them my self, as long as they make sense and they're not redundant.
let me know what you have in mind