The T26E5 upper turret armour is totally wrong, you cant pen it even with a type 99 L15A2 shell.
In the image you can clearly see the armor has been perforated, but no damage is done to the crew.
A 0° top to down shot with the same shell yields a very different result, so it would suggest the problem stands with the angle of attack, but with the shell being HE, the angle should not matter.
