Canvas Template based on Item in Another Row

I am running into an issue setting a canvas template for new rows based on a value in a table. There was an interesting solution in this community response: How to acces template pages in formula but it creates an issue for tables with data that already exists because it sets ALL row values for the canvas, which means it will rewrite any existing canvas items that might exist in the table, rather than just using a template for new rows.

It seems that the new row in the canvas functionality is limited to the selection box of that feature only:

Once you use the fill values section and start editing formulas for the cavas it replaces the existing contents in ALL rows of the table.

Does anyone know a way around this?

I’ve got an existing table with columns of notes. I suppose I could archive an old table of old notes and create a new table clean for moving forward, but that seems like a bad hack.