This is exactly the same issue as elementary OS system fonts haywire but it is unsolved there.
- I am inclined to believe this is related to screenshot tool on elementary. I was taking some screenshots in an evince window. It glitched to this font for a split second every time I tried to do an area grab screenshot. Then, it occured permanently. I can read all the fonts inside the browser application window (not the address bar or tabs though), so I kept on working thinking I'll just do a reboot later, but it persists.
- The problem does not occur in Guest Session, or a new account as I just created.