The fix shouldn't require much understanding, just change the text from one layout to the other. For instance in Mansion.gd there is:
halfsiblings.append_array(entry.halfsiblings)
Effectively "halfsiblings" is" array1" and "entry.halfsiblings" is "array2". which can be moved to the other layout:
halfsiblings += entry.halfsiblings
The existing line can be replaced with this line and it should work.
As a quick reminder, the mod system makes text changes to the game when mods are applied, so if you change the text of the mod files you will probably need to re-apply the mod for those changes to have any effect.