This was recently added to liblouis, pending the relase of 3.1: liblouis/liblouis@b4e8793
The table name is en-us-comp8-ext.utb.

This requires:

• Upgrade to liblouis 3.1 when it is released.
• Add the table to the lists of output and input tables.

Also appreciated:

• Scrutinize the table for errors and omissions.

Open questions:

• What to call this table? There is no official standard. Will the suggested name "extended computer braille" confuse users?
• Can this table supersede the current en-us-comp8.ctb table? It is a superset of the existing 8-dot table and thus backwards compatible. However, I hesitate because that would make it the default table and thus impacts a lot of users.