IMO, that's more complicated than necessary. My recommendation is to not use scenes in ISY portal, and instead assign rooms in Google Home. Lets say you assign 2 lights to the room "Dining Room" in the Home app; when you say "dim dining room lights to 30%" it will set both lights to 30%, basically replicating scene functionality.
The pain is that you have to reassign rooms any time you unlink and relink, but I still find it much better than having to put IFTTT in the middle.
If it's working well for you, that's great, just wanted to share an alternative solution for people facing the same issue. If you want to dim/brighten lights in multiple rooms with one command, your method is probably the way to go.
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