Getting column names and adding a new column if it doesn't exist

Hi all and Happy Friday! I have an interesting scenario that I’ve been beating my head against the wall with for hours and hopefully y’all can help me solve it. In the below scenario, I’m trying to get the names of existing columns in the board and add a new column if it doesn’t already exist. My problem is that I can’t figure out how to set up the filter after the router to check for an existing column name correctly. If I use it as pictured, it only looks at the first column name.
If I try to go to just the Columns for the Contains statement, it returns collections, so no match there.

Or am I going about this the completely wrong way? Help, please!