I decided to try to look at the code and see if I can hack it. In the process, I think I have found a bug in "Check missing EBOK cdetype". It seems that exth.cdetype is a byte string, so in check_mobi.py:
Code:
if exth.cdetype == 'EBOK':
always fails, and should be changed to
Code:
if exth.cdetype == b'EBOK':
Hope this helps.