Any non-ASCII characters in metadata are encoded for storage. Swarm encodes header field content according to the rules of RFC-2047 to comply with HTTP/1.1 per RFC-2616. Characters in sets other than ISO-8859-1 must be encoded.
Encoding of non-ASCII characters may appear in the metadata details for an object viewed in the Content UI:
Swarm allows all string-typed header fields to have multiple lines as well as encoded words. Swarm stores the header value as-is with the object metadata. It decode the value when Swarm needs to use that value (such as for metadata indexing). Swarm decodes header fields into Unicode and then operates on the decoded values. The original encoded persistent headers remain safely stored with the object and are returned when the object is retrieved.
See Encoding Non-ASCII Characters in Metadata for Swarm's handling of metadata.