During their recent work on the mrousavy/expo and expo/expo repositories, Guilherme focused on improving accessibility, localization, and reliability in mobile development. They enhanced documentation by adding alt text for screen reader compatibility and addressed localization issues by ensuring hooks re-rendered correctly on timezone changes, using Swift and Kotlin to observe system notifications. Guilherme also resolved a serialization bug in iOS calendar recurrence, improving scheduling accuracy. On Android, they improved print job traceability by dynamically deriving job names from file URIs, leveraging Java and Android APIs. Their contributions reflect a thoughtful approach to cross-platform bug fixing and inclusive user experience.