While migrating widget.properties values in ThemeData.xml, "xml" encoder is added for template "screencsv" which was not persent in the properties file. By this, special character are not supported in CSV file.
Steps to generate:
1. Go to Accounting section.
2. Go to Organization GL Settings.
3. Click on accounting in companies section.
4. Click on Reports submenu tab.
5. Click on Inventory Valuation report.
6. Export report as CSV.
This is committed under revision number r1806076.