Culture
Faith
Food
Gold
Production
Science
Belief_BuildingClassYieldChanges xml xml xml xml xml xml
Belief_CityYieldChanges test test test test xml test
Belief_HolyCityYieldChanges test test test test test
impl
Belief_FeatureYieldChanges xml test test test test test
Belief_ImprovementYieldChanges xml xml xml test xml test
Belief_MaxYieldModifierPerFollower code code test test xml test
Belief_ResourceYieldChanges xml xml xml test test test
Belief_TerrainYieldChanges test xml test test test test
Belief_YieldChangeAnySpecialist test test test test xml test
Belief_YieldChangePerForeignCity test xml n/a test n/a
impl
Belief_YieldChangePerXForeignFollowers xml test n/a test n/a
impl
Belief_YieldChangeTradeRoute test test test test test xml
Belief_YieldChangeNaturalWonder test xml test test test test
Belief_YieldChangeWorldWonder test xml test test test test
Belief_YieldModifierNaturalWonder code code code code code code
Neither of these three 'impl' are working for me, even with 55a.
Food and Production for YieldChangesIncomingTradeRoute do work, they are for internal trade routes only.
Couldn't make Science and Culture work, though.