Dear @TardisPilot and @ipazin,
You are right, in the current 0.8 version of our extension, formatting is applied to the default sheet only. Flow variable control is solely available for the fields exposed to the user interface.
Selecting specific sheets by name is on our development roadmap and will most probably be available in a future version of the extension. Please note however, that adding more styles to pre-formatted XLSX workbooks imposes the risk of exceeding the XLSX specification’s maximum style count limit and could hence be disallowed.
Best regards!