It will not have a significant effect on the flavor of the beer. According to the Briess website, Golden Light malt extracts are made from base malt with a Lovibond color rating of 4 degrees. Pilsen Light is made from pilsen malt at 2 degrees Lovibond. The difference between the base malt and the pilsen malt is nearly negligible, and will be well-covered by whatever specialty grains you are using to give your Irish Red its redness. RDWHAHB.