What JSON Lines is
JSON Lines is one complete JSON object per line, with no enclosing array and no commas between records. The file is not valid JSON as a whole, and that is the point.
Log pipelines, machine learning datasets and anything that appends records or reads them in a stream.
What INI is
INI is the oldest configuration format still in daily use: named sections, then key equals value lines.
Windows software, PHP, Git and a long tail of tools that never moved on.
What changes when you convert JSON Lines to INI
Each line is parsed on its own, so a corrupt record does not take the file with it. Keys are unioned across lines in first-seen order, so a record missing a field leaves that cell empty rather than shifting the columns.
Each row becomes a section named after its first column, with one key per remaining column.
What carries over from JSON Lines to INI
JSON Lines records 3 things about a table that INI has no way to hold.
JSON Lines distinguishes a number from the text of a number; INI does not, so every value arrives as text and has to be re-parsed by whatever reads it next.
An empty cell and a missing one are the same thing in INI, so a null and an empty string in the JSON Lines both come out blank and can no longer be told apart.
JSON Lines can hold a value that is itself a list or an object. INI has only flat cells, so nested values are flattened into one cell rather than being spread across columns.
The identifier 007 comes out of the INI as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.
The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a INI file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the INI.