"'In 2008, the Northern Ireland Assembly approved the reform of Local Government. The change moved Local Government from the 26 current Districts (LGD1992) to 11 new Districts (LGD2014), as well as making changes to the powers of Local Government. The geographical changes were initiated through the Local Government (Boundaries) Act (Northern Ireland) 20081. (http://www.legislation.gov.uk/nia/2008/7/pdfs/nia_20080007_en.pdf)
The 11 new Districts become operational in April 2015; the new Districts will however operate in shadow mode from April 2014. Producers of statistics should consider this in their plans for changing over to the new geographies.
Final changes to the names was confirmed on 24 February 2016.'"
I have these shapefile downloaded but have never attempted to update anything of this complexity but I am surprised that no update has yet been made. I am willing to upload these changes but I wanted to make sure that nobody else was in the process of doing this already.
A good point, I hadn't realised this was the case. There are 11 councils now; I don't think that the former 26 boundaries have been included on OSM.
I'm not aware of any other process to update this. Townlands are prominent on OSM for NI, I *think* that many townland boundaries may be analogous to council extents.