I still do not see where one has to learn the Croatian Language of you Ancestor. If someone (like I had) is applying through a parent, grandparent or great grandparent, it is still not necessary.
The article of citizenship under this cause is Article 11. This Article is very clear about NOT having to know the language.
Article 11 An emigrant, as well as his or her descendants can acquire Croatian citizenship by naturalization although they DO NOT MEET the prerequisites from Article 8, paragraph 1, points 1-4 of this Law. [Does not need to be over the age of 18, does not have to revoke citizenship of current country, does not have to live in Croatia for five years AND does not have to speak the language.]
The Law has remained unchanged for 24 years, since 26 June 1991 as you have at the bottom of your post. I applied in 2009