How to change the Type of a column without changing the content

Hi all

I am trying to change the column type. it should be Boolean Value, but some other values come in chaining the type to “?”. So I would need to / want to change the type to “String”, however, I don’t know how. I used the node “column expressions”, but don’t know hot to configure it. They way I did configure it, gives me an error

“No converter for column type ‘Non-Native [DataValue, Nominal]’ of column ‘Match Found’ exists.”