I have lots of X10 devices too.
Had the same issues and have been testing with it for some time now.
Dont think it a homey issue, but more X10 limitations.
Remember: X10 devices are not controlled directly via homey!
Homey sends out a rf signal, this signal is picked up by a X10 receiver (cm15pro or tm15). The receiver sets the signal onto the powerline which triggers the device.
Often the signal is put on multiple times.
This is were the problem occurs:
Homey fires a sequence of X10 commands, the receiver receives these but cant keep up with the speed, signals are “lost in trans,ation”
I have used 2 solutions:
1 Put a delay of at least 6 sec between the X10 commands in the flows
2 create “scenes”: I created macros running on my cm15pro. For example 1 macro switches on all 6 lights in my livingroom. The macro is triggered by a command from homey.
Solution 2 has another advantage: x10 RF can only send relative dim commands (brighter, less bright) but the cm15pro can send absolute dim commands (set to 45%).
So I have 2 scenes for my livingroom. One dimmed and one bright (when the cleaning lady is in or when homey
sets the “alarm” status)
Try it out!
My X10 is pretty stable now. Although I still have issues sometime when multiple trigger are set at the same time (when the timer triggers the dimmed status & somebody walks in the garden triggering the X10 garden lights to go on)