How do Queensland's top judges come up with such decisions?

High court reinstates Gerard Baden-Clay's murder conviction | Australia news | The Guardian

I didn't post about it at the time, as I wanted to:  the Queensland Court of Appeal's decision on the Baden-Clay murder conviction just didn't make any sense to me.   It seemed that if you took its view, you could virtually never get a murder (as opposed to a manslaughter) conviction in cases where there was no witness to the death, especially if the defendant gave evidence that it was an accident.  But it seemed particularly risible in a case where the accused himself had given evidence that there had been no fight of any kind, the jury had clearly rejected it as being untruthful, but then the defence argued effectively on appeal "so he lied, but you still can't find anything more than if he did cause her death, it might have been an accident".

The report of the High Court decision indicates that my instincts on this were right:

It noted that Baden-Clay at trial denied fighting with his wife, killing
her and then dumping her body, which was found under a bridge at Kholo
creek 11 days after she went missing.

“His evidence, being the evidence of the only person who could give
evidence on the issue, was inconsistent with that hypothesis [of
manslaughter].

“Further, the jury were entitled to regard the whole of the evidence
as satisfying them beyond reasonable doubt that the respondent acted
with intent to kill or cause grievous bodily harm when he killed his
wife.”

Yes:  if a jury considers a defendant is lying through his teeth, they are under no obligation to then give him or her the "benefit of the doubt" as to the next most innocent explanation, at least (or especially) where there is clear evidence of motive for intentional killing. 

Ever since the Pauline Hanson conviction was overturned by the High Court Court of Appeal, I have wondered how it is that Queensland's judges manage to make such wrong decisions.  (I'm pretty sure that in that case, the appeals court  was again unanimous that the trial judge were just obviously wrong.)

How do we manage to get judges here that seem so capable of poor decisions?