The occasional mention of Bitcointalk in Croatian forums about technology, IT, and stuff like that could maybe get some new people interested.
I tried that, to no avail. Thinking if it, I talked to every single person I know IRL (that is into crypto) about bitcointalk and responses I got were from "bitcointalk is one big signature campaign circlejerk and echo chamber" (that's coming from veterans) to "what can I find on bitcointalk that I can't find someplace else" (mostly coming from new people). Neither is true, but that's how they perceive bitcointalk.
It's the same thing with the 3rd most active Russian - The0ldl_lser. Not a single post in English in the first 5 pages of his post history.
Azrieli has a few posts in English, but the majority of his writing also takes place in the local sub.
That's one of the advantages of big boards like Russian, German and Turkish; they are practically self-sufficient and members can find everything inside their own board. So even if they know English to some degree, majority of them will just rather stay there.