Hello @tjezm and welcome to the Community!
EasyMorph tries to run actions in parallel where it's possible. However, if the actions update the same file, it may lead to file access conflicts that typically result in errors.
Therefore, first of all, make sure that the sheets in your Excel file are not updated simultaneously but one by one. Depending on your workflow logic, you may need to use the "Synchronize" action to ensure the necessary order of execution. See this topic for an example: Example of using Synchronize for exporting into a spreadsheet