Although Jeremy hoped Bonnie could quickly master the Magic Expert awakening talent she had acquired, it was evident that gaining full control over such a talent would require significant time and practice. Therefore, it was impossible for Jeremy to continue his actions while bringing Bonnie along with him.
Moreover, Jeremy had no intention of facing Kean alone. While he believed his own strength surpassed Kean's, traveling to the capital would place him in an isolated and vulnerable situation. Kean, on the other hand, had the potential support of the Person in the Mirror. This made it clear to Jeremy that he could not afford to take unnecessary risks.
Thus, Jeremy decided to first investigate the three spoils he had obtained from the special instance.