Held between 22-24 April in the Tatra Mountains in Slovakia, the CASTIEL2 International Workshop gathered representatives from all National Competence Centres (NCCs), all Centres of Excellence (CoEs), and all CASTIEL2 Work Packages/Working Groups for training sessions and collaborative discussions on potential synergies. The event gave the participants the opportunity to exchange on the ongoing activities, tighten the collaboration between their projects, and to discuss common goals. We thank all participants and organizers for the lively interaction, productivity, and inspiration for future joint actions.