'Papering over the cracks' is a metaphor that relates to the history of construction. In the UK Interior walls of buildings were covered with wooden 'lath' which was slathered with plaster that oozed into the spaces between the wooden lath. As the mixture dried it contracted and this caused cracks. One way to deal with the problem was to fill the cracks and repaint or to simply wallpaper the wall. The wallpaper solution didnt 'fix' the problem - it somply covered it up hence the metaphor 'papering over tthe cracks' meaning to hide the problem rather than fix it.