加泰罗尼亚成为了一个独立共和国

加泰罗尼亚是个活跃的地区, 也是西班牙最富的地区。它的进出口比率占全国的三分之一。

加泰罗尼亚人永远有自己的民族独立性。政府不得不处理这个政治危机。

议会宣布投票的结果时，独立主义者别提多高兴了。

加泰罗尼亚是个(经济)活跃的地区, 也是西班牙最富有的地区。它的进出口比率(1)占全国三分之一。

加泰罗尼亚人永远有自己独特的民族认同(2)。政府不得不处理这个政治危机。

议会宣布投票结果时，独立主义者欣喜若狂(3)。

Notes:

(1) I'm not quite sure whether 进出口比率占全国三分之一 is perfect in terms of grammar, because 比率(proportion, which is a number) should not take a portion of national import and export (which are goods,products, etc).

I think it is ok and understandable in conversations, if not perfect, but I will leave it to grammar experts. 

However, it is definitely correct to say 进出口总额占全国三分之一。(in this case, it is PRODUCTS of the region that take one third of the overall imported and exported PRODUCTS of the country)

（2）民族认同。
 I agree with the first reply. It is different from 民族独特性 which refers to the mostly objective features of a certain people. These features are either from objective observation or from other people's perception of that people.

 民族认同,or国家认同(National Identity） refer to the people's perception of their own people. It is how they perceive themselves, how they identify themselves as part of their people, and how they seperate themselves from the outside world, thus it is a subjective term. 认同 is the common translation on all kinds of such perception, at least in academia, such as 国家认同，民族认同，家乡认同等。

(3)I decided to change 别提有多高兴 to 欣喜若狂.

It is very tricky. 别提有多高兴  is actually correct, but I at least personally never use that in my life. 

Let me explain.

别提有多高兴 should be an informal way of expressing great happiness when informed of good news.

But I hardly hear anyone actually use that in my life. It could be regional though, i guess more common in the north.

I've never read it in any book for adults either.

The most possible way I can read/hear it is on children's books, children's writings and their speaking in a school show.

So, it sounds a bit childish to me, not suitable for such a big event/news.

Therefore, I would suggest you to avoid this phrase here. 

欣喜若狂 from the first reply is a very good word here. 

加泰罗尼亚是个活跃的地区（自治區, to be more specifically）, 是西班牙最富有的地区。它的进出口比率佔全國三分之一。

加泰罗尼亚人永远有自己特别的民族认同 (民族特性?)。政府不得不处理这个政治危机。

议会宣布投票的结果时，
別提独立主义者多高兴了。(it's not wrong, but not common to say like that. I'll just say 獨立主義者都欣喜若狂)