Agreed.
The harnesses / RLHF do a good job of prioritizing mechanisms to check results, which works out pretty well pragmatically for programming.
Nonetheless, I see Opus 5.5 spew out false information daily (never mind its code's unreadability).
I can't speak to Fable or Astra, because my employers, while threatening to fire us if we don't use the bullshit bots, have also refused to light the barrels of cash on fire that are required for those models.
As far as I can see, their fundamental nature has not changed, and truth is not something they have access to - just the called tool's exit code.
I've definitely seen both Labs' "best" stuff confabulate to this day.