The NTSB report is short. Just read it. From my casual look, it seems like a hand flying captain became distracted in the clouds/bumps to look at the EICAS and/or trouble shoot after a botched cleanup after T/O. I don’t know 777 procedures. Lots of possible contributing factors on how/why that could have happened but no CVR and conflicting pilot accounts.

my big wonder was why level off in an overspeed?