'itself' in the first one is an incorrect pronoun for 'manager', and is not in a very natural position in the sentence. Therefore, the manager not only has to adhere to ethical standards themself... If you want to use 'itself', use 'management' instead: Therefore, management not only has to adhere to ethical standards itself... The second part of that sentence: "their observance in the organization' is not very understandable either. (b) sounds fine to me.

I think the first one should be (a) Therefore, the manager not only himself has to adhere to ethical standards, but also has to provide his observance in the organization in general. (b) The concept consists of nine building blocks representing the company’s performance and the value it adds to itself.

Emily's beginning of (a) is superb, but if you are translating a company's guidelines or something, perhaps you need "he also has to ensure compliance therewith/with these standards in the organization in general"

I'm not sure that the performance can add value to the performance. While plausable, this seems silly. I'd suspect the "it" and the "itself" are intended to refer to different nouns, making the "itself" wrong. (b) The concept consists of nine building blocks representing the company’s performance and the value it adds to the company. Maybe?