If the frog in the Christmas Frog Story is like an ordinary frog, it might represent the overlooked or small things in the Christmas celebration that still have a role to play. It could be a symbol of nature being part of the Christmas spirit even though it's not the typical Christmas animal like a reindeer or a snowman.
I'm not entirely sure, but it's very likely. TvTropes is a comprehensive database for all kinds of fictional works. Given Konosuba's popularity, especially in the anime and light novel world, it would make sense for there to be a section about its visual novel on TvTropes. You could check by searching for 'Konosuba visual novel' on the TvTropes website.