I am wondering about how this will affect diplomacy. I have looked through the thread and I might have missed something, but here it goes. In vanilla, it was pretty simple. If an alien species asked you the following:
"These are my pink bunnybears who populate my fifth moon. Aren't they cute?"
"I am here to discuss the matter of interstellar trade. Can we form a mutual agreement?"
"Hey, I got some tasty babies I barbecued. Want a bite?"
You can kind of see who you would like to stick to depending on ideology. However, with a system like this, it becomes far more complex, and judging a species ideology a complicated matter, as you now expect others to have a completely different worldview, and the ability to quickly judge them is also quickly muddled. For example, an egalitarian species might love an invidiualist, and hate a certain other egalitarian as their worldviews are too different. In the end, ideological tree will matter little at all in foreign politics and what really should drive them is behavior. However, the exception is if a civilization is more ideologically minded (aka AI behavior) so they would pay more attention to it. Your average however Joe is less likely to care if some space slugs are communist, unless they want Joe to be a communist, too.
TL;DR: Ideology should affect diplomacy far less, as without clear good and evil it becomes a minor concern unless the civ is fanatical.