I didn't checked it without HD mod. We need the third tester. As far as I can see, crash should not occur unless WoG memory is corrupted. I loaded your savegame and didn't reproduce the crash. More testers, more experiments will be probably necessary.

HE:V limit is not changeable, because it's 4-bytes integer value with 32 bits (1 byte = 8 bits). Extra objects overwrite other objects bits and even memory after that bits.
In Hero structure exactly 10 integers of 32 bits each are allocated for storing visited objects flags (10 object types). This is hardcoded restriction, unless someone patches all places, where these fields are used.