Couple of quick observations.
My impression of an Earth equivalent of RCI values (capped between -100 and +100):
Economics:
-100: Pre-coinage barter economy. Almost everyone on subsistence.
-80: Great depression era in Germany Reich. Bad enough to burn money for warmth, but not absolute devastation.
-50: Crises of 1999 and 2007. Destruction caused by war.
-20: Africa average. Plagued by colonial history, but has positive outlook.
0: Global average.
20: OECD average.
50: 70s US boom. Golden age.
100: Unknown.
Environment:
-100: Extinction event from planetary catastrophe (KT-event).
-80: Ice-age level pressures, destruction of many biomes. Nuclear winter.
-40: Industrial revolution spread across the globe. Golden age where man "conquers" nature.
-20: Present day earth. Climate change cause regular disturbances, but damages limited to regional scales and rapidly reparable (in principle, given a space-faring civilisation).
0: Where we would like to be in 100 years.
+20: When greens would like to be in 100 years. Active habitat preservation and climate regulation.
+40:
+80: Early Jurassic.
+100: Cambrian explosion-level of biodioversity.
Medical:
-100: Pandemic in process of wiping out civilisation.
-80: Black death.
-40: Widespread epidemic.
-20: Global average before modern medicine.
0: Global Average with modern medicine. Medical research normal, but delivery is always hampered by ground reality.
20: OECD Average.
50: Pessimistic Futurist projection scenario, where we find cures for all common diseases but is unable to prevent death.
80: Average Futurist projection scenario, where we find cures for all common diseases, and is able to delay death.
100: Immortality discovered.
Public Order:
-100: Complete collapse of society.
-60: War-torn country beset by looting. Government has lost control and is ineffective.
-40: Status-quo of countries in civil war. Disruption of almost all civil services. Limits of unsuccesful martial law.
-20: Crime affects several sectors. Bribery is the norm, but society functions.
0: OECD average. Corruption/crime evident, but its influence somewhat mitigated.
20: Top of OECD. Corruption/crime evident, but is negligible. Also, a "successful" and "responsible" mafia-based public order who are able to stifle competition.
40: Limits of successful Martial Law.
50: Ideal democracy and other forms of government that still permit individual rights and freedoms.
100: Complete theoretical Utopia. (Andors start here)
= = =
In the above scheme, buildings can have both a positive effect or a zero-adjust figure. However, it's formulated such that a well-managed planet should have a resting point of +20 maximum with most of the buildings in place, and a poorly-managed one with no building at about -20. Player actions and incitements can bring this to +-50, but only game-changing events are able to bring it to +-100 (with or without player help). On a normal game, you should only see a +-80 once in a century? Not sure on game versus reality at this point.