I will try to summarize the questions,

How do I know that the bullet does not expand? I simply look at the size of the exit hole and see that there is no real difference to the entry hole. Then i look at the internal damages to lung tissue, heart and liver.

Shooting boars on driven hunt the way that we do it in Poland is a bit special, we start at 7:45 and usually finish at 16:30, we manage between 7 and 10 beats a day and there is not a lot of time to verify if there is a dead boar or a clean miss. On a boar weighing 80 kilo there may be an inch or more of fat, the fat will close any exit hole immediately if the exit hole is just one or two bullet diameters. This may lead to situations where the boar is hit really well and there is not a drop of blood to be seen at the spot.

On a driven hunt it is also important that I either trust the first shot or see a good reaction on the animal before moving onto the second boar or deer, and there is only a fraction of a second for this assessment. If there is no reaction, the animal may be hit perfectly and I waste my second shoot at the same animal that is really dead without knowing it instead of taking the next.
It is not so much the question if it kills or not, but more on how and how fast it will do so.

I would LOVE to use the Norma Alaska in cal 375, only it is not produced in this caliber by Norma. I have used it in my .308 Tikka since I started hunting 34 years ago.