You do not need to use Focus window or Send keys. There is an entire actions group called "Excel" that has actions like Launch Excel, Attach to running Excel, Read from Excel worksheet , etc.
The problem with your flow is that you're interacting with Excel the way a human would (by navigating via its UI and sending keys to copy values), when all you need to do is use native Excel actions without using the UI.
-------------------------------------------------------------------------
If I have answered your question, please mark it as the preferred solution. If you like my response, please give it a Thumbs Up.
I also provide paid consultancy and development services using Power Automate. If you're interested, DM me and we can discuss it.