Will I be affected by not teaching my maid—who has recited the Two Testimonies—how to pray and read books about Islam, knowing that she cannot read, and will I be sinful for that?

Teaching a Muslim maid her religious obligations, such as purity (tahara), prayer (salat), fasting (sawm), and the like, is obligatory. If someone who knows her language is found, then you should take her to an Islamic center to teach her. Otherwise, teach her through verbal instruction and gestures until she memorizes Al-Fatiha and a short Surah. Effort must be expended in teaching her what will enable her to properly practice her religion.