Final answer:
Caitlin's main challenge during her trip was a language barrier due to culture shock, as she could not fully understand the rapid Spanish being spoken or her host family's expressions.
Step-by-step explanation:
The question appears to have a mistake in the name, as the referenced trip is by Caitlin, not Maia. Regardless, Caitlin experienced challenges relating to culture shock during her travel to Spain, not Brazil. These challenges included a language barrier, as she struggled to understand rapid Spanish being spoken all around her and had difficulty interpreting her hosts' facial expressions. The text does not mention lost luggage or flight delays, so these were not issues that Caitlin faced. Therefore, the problems Caitlin experienced during her travel were related to cultural differences and language barriers, which falls under Overcoming Culture Shock.