Only if counsel challenged the point during the trial
Difficult as it might be, you can’t allow the judge to be wrong during the trial without calling them on it: very, very politely.
For example, there is case law that says you can’t successfully appeal because the judge was asleep through significant parts of the trial; appeals courts are clear that you have to wake them up. If you don’t then you accepted that you didn’t want the judge to hear the parts of the case they slept through, it’s your choice how you present your case. Frankly some cases are better if the judge misses half the evidence.
Of course, if the error of law makes it through to the oral or written judgement then you can appeal even if you didn’t take issue with it.