i know it may be more work, but did you try it without the patcher? Just dl the files and make the cd image yourself from scratch, or mount it like i explained before.

Your md5 hashes are correct and corresponds with HoMM original v1.0 DOS release (September 6, 1995). But you can try to replace heroes.exe v1.0 with v1.3 exe from HoMM Compendium CD1 (md5 0aac4ed9eaab48fba3863182dcb7a490).
But if you do this then you have to additional rename 2 folders: Heroes\ANIM to Heroes\DANIM and Heroes\DATA to Heroes\DDATA

Woohoo, heroes 1 got officially updated to stereo music!

I'm afraid I haven't made much further actual progress since the above. My files seem to be the same as everyone else's. However, since GOG released the new version 2.1 installer with the stereo files already in place, I've made a further discovery.

Just to check if there was a difference, I installed a fresh new copy of Heroes using the new version 2.1 installer. As before, I created the installation in a Wineskin and then used Boxer to turn it into a game package. However, this time I kept a temporary copy of the Wineskin installation and tested that, too.

Results:

1. Boxer: The game freezes exactly as before. This at least proves that there wasn't anything wrong with the music patching process on my system with the previous version.

2. Wineskin: The game works perfectly! No freeze at the expected point.

So that's interesting. I'm using the current version of Boxer (1.3.2), which is based on DOSBox 0.74 (also the latest version). So perhaps this is boiling down to Mac versus Windows environment issues? I.e. the exact same set of Heroes files works with DOSBox running under a Windows environment (emulated by Wineskin) but fails to work correctly under DOSBox running natively on Mac OS X.

NB This doesn't really explain why my previous copy of Heroes (from the V1 installer with 8-bit sound) doesn't freeze at the same point, either.

Nevertheless, that's the situation.