Can the large window in the back room of the due north house be covered with white paper? I have one now, many years ago. Is it auspicious?

Yes, there is nothing auspicious or unlucky, it is all superstition. Before the 1970s, all lattice windows in rural areas were basically made of large white paper, which not only blocked the wind but also made them bright, but was broken by a touch and had to be re-pasted, which was troublesome. Certainly not as good as glass. . Now that conditions are better, it will certainly be brighter if they are replaced with glass windows. It's best to replace the large window in your north room with glass, which is beautiful, generous and allows light to pass through, and it also lasts forever.