Found errors in database.log:
[8078.496] Invalid Reference on Building_ImprovementYieldChangesGlobal.ImprovementType - "IMPROVEMENT_CUSTOMS_HOUSE_VENICE" does not exist in Improvements
[8080.383] Invalid Reference on EventChoice_ImprovementYieldChange.ImprovementType - "IMPROVEMENT_CUSTOMS_HOUSE_VENICE" does not exist in Improvements
[8080.383] Invalid Reference on EventChoice_ImprovementYieldChange.ImprovementType - "IMPROVEMENT_CUSTOMS_HOUSE_VENICE" does not exist in Improvements
[8078.496] Invalid Reference on Building_ImprovementYieldChangesGlobal.ImprovementType - "IMPROVEMENT_CUSTOMS_HOUSE_VENICE" does not exist in Improvements
[8080.383] Invalid Reference on EventChoice_ImprovementYieldChange.ImprovementType - "IMPROVEMENT_CUSTOMS_HOUSE_VENICE" does not exist in Improvements
[8080.383] Invalid Reference on EventChoice_ImprovementYieldChange.ImprovementType - "IMPROVEMENT_CUSTOMS_HOUSE_VENICE" does not exist in Improvements