Actor John Boyega, who plays former stormtrooper- turned-hero Finn, previously referred to Tran as "the new lead".
And director Rian Johnson has now said that she does indeed play a significant role, reported Digital Spy.
"I am so excited for you to meet Kelly. She's really something special."
Lucasfilm's Creative Executive Pablo Hidalgo also praised the actress, describing her as "a great addition to our Star Wars family."
Tran, who has previously been seen in videos for comedy website CollegeHumor, joined the Episode VIII cast in January, although details of her role have been shrouded in secrecy.