Tim I think it goes something like this: There were 3 separate manufacturers, CZ, Jawa and Eso. Jawa was the bigger fish & ate up CZ & Eso. Who knows what politics were involved in it all.
The CZ symbol is & was always with CZ, originally a weapons manufacturer.
Jawa started out using some bike made in Germany called the Wanderer, the guy who started Jawa had the initials of JA so he added the the first 2 letters of WAnderer & JAWA was born.
Eso in Czech lingo means Ace, builders of speedway bikes.
Hope this helps to understand the cocktail of machinery that Jawa/CZ wheeled out of it's various factories.
Note: This stuff is all off the top of my head & is no doubt flawed with errors but until someone else who knows more about CZ's (which I'm sure there are) speaks up, this will have to do.
Cheers - Eno