Is a non-literal translation of a text without a correct citation plagiarism?
Yes, it is. Using someone else's work by re-framing it is plagiarism. If you re-frame someone's work you will have to cite your source.
Does it suffice to cite all the sources you have used at the end of your text?
No, in non-scientific or popularised academic literature you do come across a bibliography at the end of the text only, but in a scientific text you use citations where they are appropriate in the text.