I was able to install Mojave 10.14.4 b3, and there is less of a red tint than before, but I still do not see the correct colors. The graphics look similar to how they did with the red tint, but are brown and black now. Not playable, as I can't see things well enough. How disappointing! I know my Macbook is not officially supported, but I did hope that it would be playable.
Edited to add: Is there a way I can download the latest DOS2 beta from GOG without using GOG Galaxy? I can't use Galaxy because it crashes. The version of the game I am using is listed as "Divinity: Original Sin 2 - Definitive Edition 3.6.36.3440 (GOG-3)"