Hello,
Sorry for this return but I did not manage to make really significant progress because I was unable to switch off your current template, for a default one, like ProtoStar, but I don't think that this come from your Template.
The other thing I try to process, is remove in your Main HikaShop Configuration, from Main tab and in Image part, I try to remove the "Thumbnail (width x height)", it's slightly better, see my screenshot :
As you can see the only issue that remains is for image that are
higher than they are
wide, for this the best solution will be to use the
same height and width for each images, it's the best and quick solution in your case.
And as your first
9 images have different proportions, that may explain your current issue, and why these picture "break" the structure.
Hope this will help you to solve your current issue.
regards