Final answer:
Two issues in Charlemagne's reign that could have been managed differently are his heavy reliance on warfare for religious conversion and the lack of a strong administrative structure. A more peaceful approach to conversion and better governance may have resulted in fewer rebellions and more profound cultural development.
Step-by-step explanation:
Charlemagne's reign had many achievements, but it also had its fair share of challenges and issues. Two key problems that could have been handled differently were Charlemagne's reliance on warfare to spread Christianity and the lack of a stable administrative system. To address the first issue, Charlemagne might have taken a more diplomatic approach to conversion, which could have resulted in less resistance and more genuine conversion. For the latter, establishing a more robust bureaucratic system could have paved the way for a more sustainable governance structure, potentially extending the empire's longevity.
Had these issues been managed differently, there may have been fewer rebellions, and the Carolingian Renaissance could have had a deeper and more widespread impact on education and culture. The more inclusive approach to religious conversion might also have shaped a more harmonious society, potentially influencing the nature of European religious and cultural development significantly.