If you look in the Kobo Developer's Corner, the latest firmware patch thread would be
Instructions for patching firmware 4.20.14622.
The two patches that might be of interest to you are in the librmsdk.so.1.0.0.yaml file (the second is likely the one you want)..
Ignore ePub book Adobe XPGT stylesheet (page-template.xpgt):
Ignore ePub book CSS and Adobe XPGT stylesheets:
Edit: Since Kobo does not support Apple Fairplay DRM (the only software that I was aware of that supports Apple's DRM on ebooks is iBooks). I'm curious as to how you are getting the books to your Kobo. I suspect the DRM would need to be removed before sending the books to your Kobo which leads to the question of what happens if you copy the book back to your computer from the Kobo? Is the DRM removed from that copy? Is this actually Adobe ADEPT DRM and not Apple's FairPlay?