Protests in Zagreb

[FlatAssembler]

I don't see what a lack of knowledge regarding current separatist movements in Croatia has to with historical linguistics.

That's not what I meant. I meant to ask why you think you can have an informed opinion about Croatian historical linguistics based on the data from Wikipedia, when you realize you can't have an informed opinion about the separatist movements based on that?

For example, Messapian has been an extinct language since the first century, so it's unlikely to be that.

Messapian was a dialect of Illyrian or, at worst, a language closely related to Illyrian. And I think Illyrian was alive at least as late as the 12th century, after the Second Slavic Palatalization ceased to operate in Croatian, but before the Havlik's Law ceased to operate in Croatian. How would you explain away the mountain names Klek and Kalnik if not as late borrowings from Illyrian, from the same root as the ancient placenames Claudius (ancient name for Papuk) and Celenae (ancient name for Orolik)?

Wikipedia references are your friend.

Well, yes, but you can't just take what's written on Wikipedia for granted. It's a good starting point for the research about various topics, but that's all it is.