Instead of repeatedly spamming the same crappy picture, why not use either this or this? The former will sadly have to be stretched, but it should look good regardless. The latter is probably not wide enough.
Obviously would ask either author for permission, just in case.
I think you are missing the point. The reason for the "repeatedly spamming" of the picture is that it portrays numerous characters. Therefore, it belongs on numerous pages.
Although I would admit that it is a bit redundant to have it, for instance, on Pisces' page, considering that there is another picture of him where he has been cut out of the original one, meaning you show the same picture of Pisces twice.
As for the two pictures you recommended, I posted the first one months ago on The Wandering Inn page(with the artist's consent). The artist of the 2nd one, however, didn't reply when I asked him for the permisson to add it to the wikia.