I tried to run KSP 1.9.1 with the EventHorizon mod, and it shows a warning (the screen is attached). On 1.8.1 it works great with the original Kopernicus.
Logs: https://drive.google.com/file/d/1Qs_OgOw1wUmljj5MxPyD3r4hCfxYls3L/view?usp=sharing
Personally, I downloaded to previous versions of KSP mod via CKAN.The mod may be available, but the modes with which it is associated (for example, station "salute", etc.) the latest version 1.4.2