I'd suggest to replace the "WGUtil.MIN_BUILD_HEIGHT" and "WGUtil.MAX_BUILD_HEIGHT" constants in WGMerge.java with variables available from plugin's config, because these constants are in fact equal to -32767 and +32767 respectively (as stated here) and not the actual world height limits, thus making the merged regions very tall which makes them quite hard to view in BlueMap.
I'd suggest to replace the "WGUtil.MIN_BUILD_HEIGHT" and "WGUtil.MAX_BUILD_HEIGHT" constants in WGMerge.java with variables available from plugin's config, because these constants are in fact equal to -32767 and +32767 respectively (as stated here) and not the actual world height limits, thus making the merged regions very tall which makes them quite hard to view in BlueMap.