Indeed my game also crashes near point 2 of the map in post #14.
The area is DSC010.ARE (Castle Daerthmac) which uses ARD000.WED and ARD000.TIS
as resources.
Just using the original files worked well here and avoided the crash:
- export AR0500.WED from the original BG1 installation to your current override
- save that file as ARD000.WED
- export AR0500.TIS from the BG1 installation to the override (WITHOUT! renaming)