I confirmed this afternoon that my Citrix issues are definitely related to 10.13.4 being angry at Centrify Express for some reason.
In short, my Citrix sessions freeze at login until I remove and reinsert the smart card (the long version is posted in Citrix's Forums).
I'm certain it's caused by the macOS 10.13.4 upgrade as last month the smart card's keychain entry used to be called "<lastname>.<firstname>.<id_number>" but now it just says "CACNG-<guid>".