Purpur Block, You have a block named the same as the base game version of 'Purpur Block' please consider renaming to something else for clarity.

Warped Nether Bricks
No crafting entry for this, seems to be a hidden recipe - although, it looks amazing! - please add recipe + other stonecut blocks :)

Ice Slabs
Don't seem to slide the player when walking on them, although still works great with boats.

Blackstone Brick Pillar
Names not displaying correctly, presumably as they are now depreciated?

Netherwart Block
No recipe to uncraft to netherwart, possibly not in the spirit of Vanilla, so presumably intentional?

Smooth Stone
Again unsure if intended, but Smooth Stone is available via stone cutter from Stone, this is not vanilla as needs to be smelted.

Cobbled Blackstone Slab
Recipe doesn't work

Purpur Block - The vanilla block's lang file should be renamed to "purpur tiles," although I'll double check this. I might need to copy the translations for en_us into the other versions of English.

Warped Nether Bricks - These actually aren't finished yet; they'll be part of 0.5 though. We just kept them in because we had already added them previously. Also, uncrafting warped wart/nether wart will be added at the same time

Ice Slabs - I'll look into this, as it should work but may have broken at some point

Blackstone brick pillar - Yes, that appears to be the deprecated version. Placing and breaking it should yield the new version, although there should be a system in place that automatically converts them on world load. We'll look into this.

Smooth blocks in the stonecutter - While we would like to keep smooth blocks to smelting, we recently implemented a new system for stonecutters that reduced the file count by many thousands to reduce load times and increase performance. As a side effect of this, smooth blocks are now part of the stonecutter.

Cobbled Blackstone Slab - I'll look into this, its likely that we're missing recipes for the cobbled blocks.

Alright so I tested these and can confirm:

• Ice slabs don't have ice physics, but only when its a bottom slab. We'll look into this, but it likely won't be part of the next release candidate
• The translations files en_au, en_ca, en_gb, and en_nz are missing, and will be added in the next release candidate
• Deprecated blackstone pillars are the only deprecated blocks to be missing a translation, will be part of the next release candidate.
• Placing the deprecated blackstone pillars in the world should automatically convert it to the newer blockID without you needing to break them again
• Smooth and cobbled blocks will be split into their own stonecutter tags as part of the next release candidate
• Cobbled blocks are missing recipes, which will be part of the next release candidate

Thanks for reporting all of these, we'll try and have another release candidate with a fix out by the end of today.

• Lang file/Translation issues should all be fixed for rc3 (purpur having duplicates, and the missing deprecated translations)
• Smooth and cobbled blocks have been given their own stonecutter tags
• Cobbled blocks now have all the required recipes
• Recipes for the unfinished warped wart/nether brick blocks have been removed, but the blocks still remain in as creative mode exclusives
• Bottom Ice slabs not being slippery will be fixed sometime before 0.5, likely before the full release of 0.4.1