That's an incredible achievement. I hope they make it, this is surely their best and possibly only chance to qualify.they finished third in their group
I've done some googling. According to this website:
All-time Luxembourg's international football matches, Luxembourg national football team records and stats, biggest victory, heaviest defeat
Their euros qualifying record is p127, w 13, d13, l 101. Five of those wins coming in this campaign.
Apparently they're ranked 87th in the world which isn't great but is still higher than I thought they'd be.
Fair play Luxembourg!