I assembled updated PCB and it worked at least once. And it stoped working after I soldered optional LEDs.
I suspect too much heat damaged the panel.

But that is not a large problem as I have one working display and display is not critical for this alarm clock.

Anyway I finally implemented the speaker and electronics part is done. I did not make much progress to software part though, considering electronics part took more than 1 year to be done, I believe it will be reach somewhere in the future.

As for the speaker, I picked CES-26138-16L030 and CDS-25148-L100 for their sizes. Then I compared 2 speakers and felt that CES-26138 sounds better and used it.

By the way, I used this repository to test display.