Lithops and Pleiospilos do not require the same care, though both like to grow on the dry side. I water my indoor Pleiospilos every 2 weeks or so year round with no seasonal adjustments, and it has lasted several years. On the other hand, you really need to leave the Lithops alone during their season of rest.
Regarding the question of light, this is a very dangerous time of year to be moving indoor plants outside into the sun. My normal process would involve a couple of gradual steps from bright shade into morning sun and then eventually midday sun, over the course of several weeks. Indoor sun is much kinder than outdoor sun because of the more moderate temperatures and the fact that regular window glass cuts a lot of the UV. My indoor Pleiospilos enjoys hours of daily indoor sun by a SW-facing window, and I would recommend the same given moderate temperatures and good airflow. At this point I can't say whether the damaged plant will recover, but it has a much better chance indoors with good light.
