The FLASH2020+ project, a collaborative effort involving various factions from DESY and the University of Hamburg experimental physics department, has been studying advanced concepts in beam dynamics, accelerator, and FEL physics. The recent FLASH2020+ 4th Start-to-End Simulation Workshop successfully bridged discussion gaps between members of DESY, the University of Hamburg, and external collaborators. It focused on realistic start-to-end simulations, efficient Artificial intelligence-based machine operation, sustainable programming and software development. The insights from these works and discussions provide valuable information about FEL output, aiding researchers and scientists in their investigations before conducting experiments at DESY. The simulations team for the FLASH2020+ thrives on collaboration and innovation, paving the way for a brighter future in scientific exploration.