번역 - 영어-세르비아어 - Translators-interested-translated

Why are they 2 sentences for this one?

Because the english translation is gramatically incorrect. It should read:

The translators only interested in your project. You can search for the texts to be translated within the project area.

That's not what I wanted to tell with this text. I wanted to say that the translators who only want to translate your project (and not the other cucumis.org translations), can search for the translations of your project.
Is it more clear to you?
I would be interested if somebody can turn the english sentence in something more fluent .

I think the way you should word the sentence is the following:

Translaters who are interested in translating in your project only, may search your project area for text to be translated.

This is very specific as to what the translater can do.

I've made a change on the english text. Is your serbian translation is still valid with this meaning?

Yes, both Serbian and Hungarian translations reflect the same wording.