During September 2025, Karl Kallman focused on enhancing the EPPlus repository by addressing a targeted bug related to Excel comment font styling. He resolved an issue where underline formatting was not preserved when copying comments, thereby improving data integrity and visual consistency in Excel exports and imports. Karl approached the problem by adjusting the XmlHelper component to correctly handle underline values and by adding a dedicated unit test to verify the accurate copying of comment styles. His work leveraged C# for implementation and incorporated skills in Excel automation, unit testing, and XML parsing, reflecting a focused and technically sound contribution.