@ Duncan1246 : You are right. I apologize for the confusion. The mod was published the wrong category on NexusMods.
I uploaded the latest version in the Grimrock 2 category.
http://www.nexusmods.com/legendofgrimrock2/mods/91/?
I'll disable the mod in the Grimrock 1 after a while.
@Torst : Thank you !
@hansbleeb : About the pressure plate underwater, here is what you need to do :
Simply leave an object on the pressure plate. Two of the pressure plate are a bit far away, so you need to throw different object with different weight if you want it to land exactly on the pressure plate. For example, a heavy weapon.
A little anecdote concerning this puzzle :
One of the puzzle I implemented a year ago, used pressure plate. It was a puzzle that required severals "steps" to complete, but I didn't know about the physics/gravity and the weight of the object that was implemented in Grimrock. In otherwords, the weight of the object you throw will affect how far they go. One of my beta tester, she send a heavy object right on the proper plate, bypassing the whole puzzle in a single throw. My jaw brokes and I had to rethink the whole puzzle !

Concerning the water spell, it's not the same water spell that you might have encountered in others mods, but the effect/implementation should be very similar. I beleive mine is from AndarkRainor (not sure, I did use some of his spells in his spell pack though - credited of course). It's not the same "gesture" too. I just re-tested and I couldn't reproduce any crash with a the "wrong" gesture of the spell though with the screenshot you provided.
About the frostbolt and the magic bridge :
Once you cast the frostbolt in the "pipe"/receptor, walk on the moving magic bridge, you will find a passage on the left. Now, you must be really quick. Kill the creature, get the spoils on the altar and run to the magic bridge, which continued to move ahead. If you were quick enough, you will be able to step on it and move to a secret area.
You are correct, the fire and ice trial is really hard, even for me !
This trial is actually divided in two part. In the first part, you need to find and activate a lever. That will add a magic bridge to the second part. Reaching the "safe" spot in the first part of the trial require you to dodge the fireball and frost bolt. If you look at the pressure plate, you can see which one will send a frostbolt, and which one will send a firebolt. There is also another trick : Use the Force Field spell as a shield against some of the magic bolt by casting it between you and the projectile, or casting the force field around you !
Now the second part, you will cross the water and look carefully at the plate and test them to "feel" the delay. They aren't as fast as those in the first part. It's on purpose. On the second part, you will have to fight a mini-boss : an Ice elemental, while walking and avoiding his projectile and those coming from the ceiling. There is a safespot on the left, with no plate. Also, there is a red pressure plate. Stepping on it will throw fire balls. This can be use against the Ice Elemental. This whole trial has at least two smaller secrets !
Thanks for playing !
Vand