I guess OP has somehow dealt with the problem but I will post what I was able to find out when I tried to solve it without AutoHotkey (as I wanted to use these shortcuts in different programs, not via .ahk script) - maybe it will be in any way helpful for future readers. And spoiler - no, I didn't manage to make it work like I want but I discovered a few interesting things.
= combination, which I guess launches Windows Magnifier program in OP's case (as
+ are on the single key on most keyboards and it seems Windows treats
= same in the case of that program) so I focused on it.
How to Permanently Turn Off Windows 8 Magnifier program.
Unfortunately, disabling program doesn't free shortcut and it is still visible as taken for other programs. I would say that there is a possibility that making custom Windows installation disc with deleted Magnify could lead to free shortcut but I can't check it.
Next I used link from OP's question and combined it with Virtual-Key Codes (check JBert's comment on non-printable keys).
Again, no matter what code I used and what keys I pressed, this special shortcut stays taken.
In my last attempt I tried using group policy - registry method is in OP's question, method via
gpedit.msc is described here.
What is interesting - this group policy turns off most of the shortcuts but not all of them. For example
X is still going to work as well as
L, Magnify and Narrator shortcuts.
It seems all shortcuts connected to accessibility in Windows (like
=) are treated specially and cannot be simply turned off via DisabledHotkeys as Explorer isn't the process that uses them. After a little bit more searching I found this article from Microsoft dealing with the topic of disabling
Win key as well as all accessibility shortcuts in games - but I have no idea how to utilise this code into something useful.
There is a simple way to turn off all accessibility programs in Windows by using Icedog's answer from Disable Narrator shortcut key in windows 8 (creating registry key for AtBroker.exe). It will prevent launching any accessibility program but shortcuts are still reserved.