I see your API resembles very much what I had to do to the original noncubic mod to get my industrial:white_brick in a sloped version. (right above your comment
http://forum.minetest.net/viewtopic.php?id=4297&p=4)
That is a plus. I like that the new sloped nodes in your version also takes name after the mod that registers the sloped node. That way future creative inventories or recipe pages can have sensible searches.
I put the material first instead of last because I think this is an extension of the basic block so names should follow the scheme of <material>_<extension> instead of <extension>_<material>. That way sorting algorithms will have an easier time ordering like blocks.
One thing I'd like to see is the circular saw and milling machine merged into a single CNC machine driven by the technic mod.
If you care I'd like to work with you on something like that.
Also I'd like all of these blocks out of the creative inventory and just have the CNC machine there.
There are so many blocks to chose from but creative mode should also (imho) make use of the machines to get some sense of usability for those.