I was playing SevTech, and the Astral Sorcery version used there is relatively outdated (1.8.0) and I wanted to play around with the observatory. I simply replaced the previous .jar with the 1.9.4 update, and the cross-mod interaction between Geolosys and Astral Sorcery suddenly broke. I tested this in a new world. If I get within rendering distance of a Crystal Cluster, whether it be on screen or not, I crash. My whole game freezes for about two seconds, then goes to full white for another five, and then shuts off and produces this error:
crash-2018-08-27_18.36.18-client.txt

Here is latest.log:
latest.log

That's because there's an orestages API change there. AS 1.9.4 had an update for that API change. You will need to update quite a few things, besides just AS: geolosys, orestages/gamestages, AS, and probably something else I'm forgetting.