What Plain Text is
Plain text here means columns lined up with spaces, the way a command line tool prints a table.
Terminal output, log files, fixed-width exports from older systems.
What MediaWiki is
MediaWiki table markup opens with {| and a class, marks headers with an exclamation mark and rows with |-.
Wikipedia editors and anyone running a MediaWiki install.
What changes when you convert Plain Text to MediaWiki
Two shapes are handled. If the same character positions are blank on every line, those gutters are treated as column boundaries, so values containing single spaces stay intact. Otherwise the lines are split on runs of whitespace.
The wikitable class is applied, which is what gives the table borders and header shading on Wikipedia.
What carries over from Plain Text to MediaWiki
MediaWiki can express everything plain text holds about a table, so this conversion is about shape rather than loss.
MediaWiki marks its header cells differently from its data cells, so the first row is written with that marker.
The identifier 007 comes out of the MediaWiki 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 MediaWiki file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the MediaWiki.