During their two-month contribution, Guilherme worked on enhancing accessibility, localization, and calendar reliability in the mrousavy/expo repository, focusing on both iOS and Android platforms. They improved documentation by adding alt text for screen reader compatibility and addressed localization hooks to ensure accurate reactivity to timezone changes. In expo-calendar, Guilherme resolved a serialization issue affecting iOS recurrence rules, ensuring correct day-of-week handling. Later, in the expo/expo repository, they improved Android printing by dynamically deriving print job names from file URIs, increasing traceability. Their work demonstrated depth in bug fixing and feature development using Kotlin, Swift, and Markdown, emphasizing maintainability and inclusivity.