Did you mean to insert all 7 wires into one single port? Or did you mean insert 1 wire to each port and run them in parallel? I can’t imagine how the former could work, or if it does for a short period of time, how it can work more than a few minutes. If you look at the datasheet of the triac:
https://www.mouser.com/datasheet/2/848/Z0103MN-1846818.pdf
the maximum amount of current it can drive is 1A. If you evenly divide that by 7 valves, each only gets 140mA, which is way below the holding current of a sprinkler valve. This is waiting for trouble to happen, either the triac will burn out, or the solenoids will not reliably open because of the low holding current. Maybe your valve draws less current? Is it a special type of valve that draws less current than other valves? The link you provided cannot be opened so I can’t check its spec sheet.
I am still puzzled by why can’t you use 7 ports and have the zones run in parallel. Is it because you don’t have enough zone ports? You can always get a zone expander to add more zone ports. In the firmware you can set these zones all to parallel, and that way you create a program, run each zone 1 hour, they will all turn on at the same time, so they all finish together. I just don’t understand why this is not a feasible option?