Been a while since I've been on but looking at this job and I'm looking for others opinions on how they would manage the transition from wood to concrete. The new ply floor is sound.
The ply looks a bit all over the place to me. My preference would probably be take up the ply, put down whichever thickness or wedi type board to get the levels near enough, then level it all, uncouple and tile most likely.
Self levelling compound, to level with
ply, cover all ,with Hardibacker or similar . Then tile. ( observing manafacturers requirements and good practice.)