(This issue is part of the i18n review of RDF 1.2 TriG.)
From section ‘Escape Sequences’
A numeric escape sequence MUST NOT produce a code point value in the range U+D800 to U+DFFF, which is the range for Unicode surrogates.
These escape sequences (‘\u hex hex hex hex’) are the same as in RDF 1.2 Turtle and there is an issue w3c/rdf-turtle#131 on that spec (about allowing surrogate characters).
Whatever the outcome of that issue should be applied here, too.
(This issue is part of the i18n review of RDF 1.2 TriG.)
From section ‘Escape Sequences’
These escape sequences (‘\u hex hex hex hex’) are the same as in RDF 1.2 Turtle and there is an issue w3c/rdf-turtle#131 on that spec (about allowing surrogate characters).
Whatever the outcome of that issue should be applied here, too.