Catching up with the thread, I discovered that for some time KindleUnpack has experimentally been able to unpack dictionaries, and possibly can even unpack inflections!
Using the current release of
KindleUnpack Calibre Plugin
I tried it successfully on a set of dictionaries

Thank you developers.
But it would not work on
my homebrew NADSAT dictionary and reported the following:
Code:
calibre, version 2.8.0
ERREUR : KindleUnpack - The Plugin v0.77.0: 2
Traceback (most recent call last):
File "calibre_plugins.kindleunpack_plugin.extraction", line 186, in unpack_ebook
File "calibre_plugins.kindleunpack_plugin.utilities", line 282, in unpackMOBI
File "calibre_plugins.kindleunpack_plugin.core.kindleunpack", line 870, in unpackBook
File "calibre_plugins.kindleunpack_plugin.core.kindleunpack", line 793, in process_all_mobi_headers
File "calibre_plugins.kindleunpack_plugin.core.kindleunpack", line 581, in processMobi7
File "calibre_plugins.kindleunpack_plugin.core.mobi_dict", line 204, in getPositionMap
KeyError: 2
Thought I would just bring it to your attention.