Juneyao Airlines did not board the plane, but the flight was delayed. Can I issue a delay certificate?

It can be opened.

Under normal circumstances, regardless of the departure airport or arrival airport of the delayed flight, you can go to the check-in counter of the corresponding airline to issue a delay certificate. However, a small number of airlines can only issue delay certificates at the departure airport.

Proof of flight delay is required:

Just provide your ticket purchase document and the flight number of the delayed flight.

Under normal circumstances, as long as the flight status can be checked through the computer network, the check-in counters of most airlines can issue delay certificates to passengers at any time.