Is the woman who supported the purchase of a television, which later turned out to receive channels containing Sharia violations, sinful, and what should she do about that?

If you requested a new device and you knew or strongly believed that they would use it for unlawful purposes, then you are sinful, because it is cooperation in sin. However, if you did not know, there is no sin upon you. What is required of you now is to advise them, enjoin them to good, and forbid them from evil with a good approach. You are not required to break the device. It is sufficient for you to condemn their actions verbally and to distance yourself from them when they engage in unlawful acts. By doing so, you have fulfilled your obligation. And whoever repents from a sin, their repentance is accepted, and the lingering effect of their sin among people does not harm them.