It occurs to me that Lucca is not only too far advance for her time, but also acts in a way that seems to make it appear that she knows more than she lets on.
She not only grasps the situation almost imediately, she creates the gate key in a very short amount of time. She also is obviously responable for buildng the first robots, which is Gato, and later we see this model only appear in Black Omen that was designed and built by the Gurus. She has amazingly high levels of technology considering the computers are in no way shape or form even close to being invented.
Further more she starts off with elemental magic, unlike any others. Not only that but a gate opens convienently to her mother's accident when she thinks about it. Some may say this is because of "the entity" over hearing what's happening, but then it's got to be asked why Lucca and why such an insignificant event?
Strangely enough this also happens one other time in the game, during the Reunion ending when Gespar opens a portal to give them the time egg, showing that he has power over the gates.
Lucca shows almost uncanny lack of reaction to a lot of the things that happen when she would be one of the most likely to be getting giddy as she would have the chance to explore the thing she loves, technology and science, but instead she seems to know exactly how to and when to do things.
We also know that Balthasar influenced, nay, triggered the events of CC, and he had long finished the epoch and would have had more than ample time to go back and set up certain events, but him not beng a warrior would not have been able to change things by himself. He and Gespar both show 2 things which lead me to believe that they influenced CT as well. They show a knowledge of things that they, even if they did time travel and watch time, would never know and also they were the only ones that were capable of setting up the sealed items.
Given this, Lucca seems to be working with the Gurus, and she is in a great position to relay information and trigger certain events. This seems to be proven simply by the sheer technology level of Lucca which is on par with Zeal and far more advanced than 2400AD which is just impossable given that Lucca's inventions would have been all throughout that era and much more advanced.
Another thing that may be just a coincidence is that Lucca, Crono, and Glenn. All of which seem to have been pretty much hand picked for this adventure have Purple, Red, and Green hair which none of the other characters in the game have those colors. This could be due to genetic alterations done to them by Gespar and Balthasar to make them stronger. Note that Crono is the strongest and balanced, Glenn is the only person to be able to wield the masamune from what we understand, and lucca is not only super intelligent but also xtremely magically powerful.
Balthasar had the oportunity and the reason to do it as did Gespar. Lucca could have been Balthasar's protegee, and it's just kept secret..She afterall later helps with the Kid project with could very well be an extension of this project. It even makes sense with the title. these events trigger CC events.