Russian/Slavic has borrowed a lot of military and 'government' terminology from both German and French, but not Tsar/Czar/Csar - at least, not directly. The title Caesar was granted to Tervel of Bulgaria by Justinian II in around 705 CE, and Simeon I of Bulgaria formally adopted it as his official title in 913 CE as Tsar. As far as I know, that was the first adoption of the title in any Slavic state/language, and it was a straight Slavicization of Caesar. The title Tsar was used by Church leaders in Kyevan Russia, but never by the princes (secular rulers) of that state. The first use of Tsar in Russia proper was not until 1547 when Ivan IV started using the title in place of his original title: Knyaz - which is Slavic, but was originally adapted from the proto-Germanic Kuningaz, usually translated as 'king' (but sometimes merely as Noble, which is also true of Knyaz). Since Caesar and its derivitives generally meant Emperor, Ivan was giving himself a promotion. Since he was Ivan the Mighty (Ivan Grozhnyi), nobody was about to call him on it.