A lot of footguns and performance optimising mostly. For triples it would be around reifying and ranking (with RDF-Star helps with but doesn't solve) and the S

A lot of footguns and performance optimising mostly. For triples it would be around reifying and ranking (with RDF-Star helps with but doesn't solve) and the SPARQL syntax still feels like a esotetic syntax at times. Cypher is OK, but doesn't really follow any existing paradigms, and LPGs can be a massive footgun without a semantic layer since you can pretty much throw any property on a node type. Federation over named graphs, or different sources as well.