If RDR syntax is used in conjunction with string literals that contain language, a parse error results. Example:
<<entity:Q16 v:P1451 "A mari usque ad mare"@la>>
wikibase:Rank wikibase:PreferredRank ;
q:P805 entity:Q41423 .
This produces exception with message:
Caused by: java.lang.RuntimeException: Could not load: url=file:///dump-3m.fixed.ttlx.gz, cause=org.openrdf.rio.RDFParseException: Illegal language tag char: '>' [8287|line]
A stand-alone test case can be seen here:
If a space is added before ">>" then it seems to work but I'm not sure if that's the intended syntax as it doesn't require spaces in all other cases (e.g. IRI or literal without language tag).