The software you mentioned and used isn’t the official software. I understand your reasoning but do encourage you to try the Unified firmware before concluding the software is bad. Guide: https://opensprinkler.freshdesk.com/support/solutions/articles/5000524845-initial-configuration-of-raspberry-pi
Furthermore, OSPi is more for advanced users who wish to tinker with software and the hardware whereas our Arduino solution is a fully assembled ready to go device with the official software preloaded. I highly encourage not choosing OSPi if you want a solution that just works.
Thank you for your feedback!