I had posted over in that thread but as this is the correct area for it. Here is my post from there.
Due to recent computer issues (massive virus had to reformat drives and lost everything) I had to have another go with installing the VN. Several hours of it gave me the old errors again, no permissions, system cannot find the file specified, etc, you've all had this. Eventually I managed to get it working. Without needing to set your system to Japanese. While I did manage to get this working on my PC I have not yet had feedback from others I have attempted to help. In addition this guide was written with me attempting to remember what took me some hours to achieve, so uh...no guarantees.
I'll detail the steps I followed and hopefully you may have some success.
First download and install HF Applocale 1.1.2
Next download and install the Moenovel version. I installed it straight to C: under the folder "if my heart had wings"
https://dl.dropboxusercontent.com/u/22064793/Screenshot%202014-12-30%2013.19.33.png
Next copy all the files from the restoration patch into the folder and run apply_diffs.
let it run until the message "press anykey to continue" appears, it may take a while.
run the game in english just to get this box https://dl.dropboxusercontent.com/u/22064793/Screenshot%202014-12-30%2013.22.35.png
tick the box for "dont display this dialog at next startup"
close the game
run applocale (you may have to find it) https://dl.dropboxusercontent.com/u/22064793/Screenshot%202014-12-30%2013.25.39.png
follow the steps, selecting "launch an application" browse your "if my heart had wings" folder and select AdvHD
next
select the language at the very bottom should look like this https://dl.dropboxusercontent.com/u/22064793/Screenshot%202014-12-30%2013.28.49.png
click "create a shortcut to always run this application with AppLocale"
title it "if my heart had wings" and click finish.
at this point for me the shortcut didnt actually appear on my desktop or anything, I'm on windows 7 so I typed in the search bar on the start menu for it. its the .exe file without the icon for the VN. drag it to your desktop.
double click to open and viola!
I have had reports from some that say this works and other that say it doesn't. (Thanks Kyuubi and CapnBlaze above for the feedback) Installing the patch seems to be very hit and miss so I can only post what worked for me but that's no guarantee it will for you.
Best of luck