However the output now needs further formatting as it's printed with brackets etc. I tried adding a print statement but dd still prints everything.

You can print @cols any way you want, using a regular print or printf, instead of Data::Dump, which is just a debugging aid. If you could show what code you are trying and what output format you expect, we could help better (How do I post a question effectively?). Also, note I updated my node right around the time you replied, check out the update too.