This is one of those "system isekai" ones that are so prevalent in Chinese fiction that they don't even bother explaining them anymore, right? I remember someone mentioning stuff about that at some point, possibly in the thread for "Please Bully me, Miss Villainess".
That's prob why it seems so convoluted
Yep, you are correct!
Others have already explained it here but I'll throw in my two cents as well.
"System" stories are basically about characters being transported into a fictional world, where they are given missions to either progress the plot of the story, or given missions to change the plot of the story, often to save a character who is doomed to tragedy otherwise.
Some stories, such as Please Bully Me Miss Villainess, have characters who rebel against the "system" and try to resist doing the missions because they don't agree with the plot that they are supposed to follow.
In this story the protagonist was put into this world to change the original plot of a story. The "original" plotline of the world was that it was essentially a palace drama focused on Xiao Qianxue becoming the favored consort of the emperor Yun Shao. The story is a drama but also a tragedy, as it turns out that while Xiao Qianxue became the emperor's favorite woman in the imperial harem, the emperor's love for her was fake, as the emperor hadn't gotten over their first love. This caused Xiao Qianxue a lot of pain and suffering, and then ultimately she grew to hate the emperor and poisoned him.
Our protagonist's mission given to her by the "system" (in this case the system seems to take the form of a little fairy) is to make the emperor fall for her instead, to save Xiao Qianxue from heartbreak and tragedy.
To do so, there are smaller missions, which once completed will give reward points that can be exchanged for powerful items to help the protagonist. In this case she had the little talisman that caused 3 seconds of random infatuation for the emperor, but as she completes missions (like increasing the emperor's favorability with her, like in a dating sim) she will likely unlock new items and more powerful abilities.