Very nice! Thanks for sharing.
I do have same setup just only 3 valves. And no pump, I get the water from the town supply. Same Fibaro double relays and 24VAC valves.
Just a tip, thought. Especially that you mentioned some z-wave range issues. Before the antenna mod Homey antenna mod, I also had some range issues with the irrigation double relays. One day the garden irrigation did not stop. Neighbour came to my door as the water started to flood onto the the street. Since then I implemented a couple of things 1/ a second “turn off” in the same flow delayed by 10sec in case first is missed, at least another chance to pick up the second one, and 2/ push up notifications when irrigation starts and then when it stops, this last one can trigger me when I check my phone and see a start but no stop.
Wished I would have a soil humidity sensor. However, I do have an industrial flow meter (very compact and free from the company I work with 
which gives me a pulse output for each litre of water, and wired into a Fibaro Smart Implant. Then I just feed the amount of water I need depending of the area (garden, lawn, etc). The downside, I had to fit in the enclosure another power transformer as these run on 24VDC.
Are those 22mm push buttons on your enclosure for manual control?
