You can ask Resolume if a column is selected by sending a string question mark to addresses like: /composition/columns/1/selected
You can also ask about all the columns in one message by sending ? to: /composition/columns/*/selected
This will return all column selected states.
The selected column might not be the one where clips are playing though.
I you'd like to launch the clips of the previous or next column, you can use the /composition/connectprevcolumn