Hungarian Academy of Sciences (only monochrome available to public)
Anybody familiar with the Voynich Manuscript will find the Rohonc Codex a similar story - book of unknown origin, unidentified script, uncertain language, cryptic illustrations and suspicions of forgery. But the Rohonc Codex remains fairly obscure, not even attracting much kook attention (so far anyway).
One reason may be that it seems to have been little known outside Hungary until recently. Nearly everything in English that I can find draws almost exclusively from Wikipedia which in turn draws from extensive sources, all in Hungarian except two (in English and German). Almost the only other writing in English with original research appears to be the Passing Strangeness blog and a brief mention in a piece on the possible forger in Janos Bak's Manufacturing a Past for the Present. (This view may be skewed by my use of English-language databases. For all I know there's extensive literature in Europe but I doubt that.)
The Rohonc Codex also just isn't as interesting as the Voynich. Look at the images below and you'll see that it appears more clumsy and the illustrations more crude. Though the images mix religious traditions there's nothing like the unidentified (or invented) ones in the Voynich.
A quick recap in case you don't want to follow the links. The Rohonc Codex was part of a count's library donated to the Hungarian Academy of Sciences in 1838 - there are no records about where he acquired it. The codex was studied periodically during the 19th century until one scholar suggested it was actually the work of Sámuel Literáti Nemes, an antiquarian of the time who did in fact create several known forgeries. Since nobody has come up with a plausible explanation for the text opinion has remained divided whether it is in fact a forgery.