I live in Zone 8b and find that my tridents dieback occasionally as well. I attribute it to frost after the leaves have just started to open and or strong winds on colder winter days. The areas most affected appear to be the newest growth on the apex or newest growth on the longest extensions.
On the positive side, they recover quickly and branches are usually easy to replace or reshape on tridents. The problem seems to be primarily with young fast growing developing Tridents.
Not so much with older trees where i am restricting the growth.
Thank you for sharing your experience. I’m glad that you find die back to be less on older trees and you’re right, they do seem to recover.