Worked on the EPPlus repository to address a targeted bug affecting the copying of Excel comment font underline styles, ensuring accurate preservation of formatting during Excel exports and imports. The solution involved adjusting the XmlHelper component to correctly handle underline values when comments are duplicated, thereby maintaining data integrity and user-visible fidelity. To validate the fix, a dedicated unit test was added to verify that comment styles, including underline, are copied as expected. This work leveraged C# for implementation, with a focus on Excel automation and XML parsing, reflecting a methodical approach to resolving nuanced issues in spreadsheet data handling.