Here are some recommendations for completed sweet romance novels with the theme of characters traveling through books:
1. "飼養(yǎng)反派小團子" by 云上淺酌: This novel follows the protagonist, 寧婧, who has a system that allows her to raise villainous characters. The story revolves around her nurturing these characters from their childhood.
2. "女配是打臉狂魔" by 畫星河: The main character, 楚澄, becomes a supporting character in a modern sweet romance novel. She gains a system that grants her power whenever someone lies to her. The story explores her journey of self-improvement and her ability to see through lies.
3. "我不介意你又丑又瞎[穿書]" by 美人無霜: The protagonist, 蘇悅, transmigrates into a book and becomes a cannon fodder character. Determined to change her fate, she transforms herself and helps her husband regain his sight. The story focuses on her growth, revenge, and the sweet moments between her and the male lead.
Please note that these recommendations are based on the provided search results and may not encompass all completed sweet romance novels with the theme of characters traveling through books.