Talend Open Source needs Dynamic Schema for Delimited files. Only the commercial version allows dynamic schema.
We need to build a component called tFileInputDelimitedExtract. You could use tFileInputCSVFilter as a reference for the implementation. Unfortunately I don't have the time at the moment for this implementation but at least let me enunciate the specifications for it in case someone decides to go further with the implementation. It could be a good project for someone willing to learn talend component creation for example.
At the moment a quick "hack" for new unexpected inner columns would be to use 'cut' to exclude them. Below we remove the 7th unneeded column from a pipe delimited file: