Expression builder in ArcGIS Online does not work for all languages.
Last Published: August 19, 2015ArcGIS Online
Bug ID Number
September 21, 2014
March 30, 2022
The issue is a duplicate of an existing issue. See the issue's Additional Information section for details. Customers associated with the duplicate issue are automatically attached to the open issue.
Solution is to escape non-English characters with a 'N' before the string. The Help for Field Calculator is expected to include this.