3ICE.HU

These Terrain IDs i copied somewhere from your site, is Underground Lava the same as Underground Ice?

No, but they are both bugged. In version 1.20 lava was blue and Ice was red. Weird, right?
I am not sure if they fixed it in newer versions, didn't test it yet.

Edit: By the way the list can be found in post 1014

Edit2: I just noticed there is no Ice on the list, it was called Lava Cracks when I collected the IDs. That's another weirdness.
I am sure with a little experimenting you can find the right values to use.
Post your findings and I will update the list to reflect the current version of Warcraft.

Edit3: In the near future, I will replace things like 'Nsnw', 'Nice', 'Ldrg', etc with long integers like 125423174. (So you can use GUI functions to change the sliding/kill terrain ingame.)

After some tries i found out that "Glvc" (Underground Lava Cracks) is the blue cracks in the Underground Tool Palette.

So everything is in order then.

Did they fix this in patch 1.23 - 1.24b?

No clue. Why don't you check it?

Because I procrastinated.