CSVs that Bananatag outputs are in UTF-8 format, however, by default Microsoft Excel uses ANSI encoding which causes many special characters such as Chinese Characters/logograms to display incorrectly. There are steps you can take within Excel which usually resolves this issue.
Within Excel, select Data → Import External Data → Import Data/Import From Text → Choose 65001 Unicode (UTF-8).
Save your settings then re-open your file - you should see this issue resolved.