Thanks for your help!
I ended up creating a new party... My choices were about the same, except that I gave levels in Item Lore to everyone except the mage (not enough points, he'll get some later).
Ian is best at poles,
Arielle is an archer,
Nathan is specialised in trap disarming, locks picking and using poisoned weapons and throwing weapons,
Catherine uses bashing weapons and is knowledgeable in Mage lore, Item lore and Alchemy,
Edwin is the wizard of the group, and is good at Mage lore,
Rayna is the shaman and is also good at Mage lore.
I also changed the graphics; I was using the old ones only, now I'm using the old terrains and Monsters1 sprites alongside all the other new ones. I had to edit Monsters1 because the "living" statues do not use the "not living" statues sprites.
Here is my new party, from the left to the right, Catherine, Edwin, Rayna, Arielle, Nathan and Ian.