Copy text from sub-item to another column

I tried searching but could not find what I was looking for.

I am creating a formula column that if a keyword is contained in the Sub-item name that it will assign the letter E, S, and/or G in the formula column.

The formula I created does not allow me to select the ‘sub-item’ column.

I tried to create an automation as well, but it I can’t seem to select the ‘sub-item’ column still.

Thanks.