Primord

By looking at the image you provided I see it failed to extract the DBC/DB2's as well not just the maps. My guess is that either your client is corrupted or it's not fully downloaded (just because you can play on the client doesn't always mean it is 100% complete). When in-game, hover your mouse over the Menu icon, there will indicate if your client is 100% or still downloading. I'm not sure if your client language has anything to do with the error. Might worth to try a enUS or enGB client version which are the most common.

After you applied the Full DB and the Alpha updates, try to do this: From what I understand you need to manually find the missing instructions in the world updates from the core and apply them. But don't apply all, it will mess up your DB, only apply what is strictly needed for the core to start.

Then I guess we have no other choice but to use the synced DB/core and wait for a next revision.

That is exactly how I did it following the same logic and everything seems to work very well (at least for an alpha). The only scenario in which I find this a bad way to do it is only if the devs created bugged sql code after TrinityCore_4.3.4_DB_Alpha which executed without error but damaged the DB. EDIT: deleted a link.