Product's name served as a source-identifying device for trademark claim, as the plaintiff is the person who produces things of this name.
Light-based art installation is protected by copyright, not trademark.
No error in denial of leave to amend.
http://media.ca8.uscourts.gov/opndir/18/08/164483P.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.