I did some research but not getting anywhere. выполнение is probably not the right thing and успех seems to be too... casual? The term should express that it is about fulfillment of spiritual needs.
For instance how could these sentences be translated into Russian:
He tries to find fulfillment in being perfect in his job.
She tries to find fulfillment in cleaning the house until it looks polished.
I don't think there is a direct phrase in Russian that confers the same meaning as find fulfillment in English. There are a couple of Russian idioms that can be used - depending on context - to provide a translation. One of them is найти себя, although it's more often used to describe something that has happened:
Он нашел себя на этой работе
The other options is to use word удовлетворение (literally satisfaction, which could be considered a synonym in this context):
Он пытается найти удовлетворение, достигая совершенства в своей работе.
Она пытается найти удовлетворение, убирая дом, пока он не выглядит вылизанным.
I would just use "реализовать себя" (реализоваться also works coloquially, but somehow does not sound exactly right) when it is in more general sense (i.e. to make one's life happier and more meaningful). Though, it does not work with cleaning the house, as it has nothing to do with spiritual need. But it works with things like travel, work, family, science, creative work, helping other people etc.:
Он пытается реализовать себя, достигая совершенства в работе / идеально выполняя свою работу etc.
In a less "precise" language the following also sounds kinda OK: "Он пытается реализоваться, идеально делая свою работу".
Also "выразить себя" (to express oneself) may work if it has to do with the desire to find a way to express your personality in your life. Still.. Maybe it is not my business but it seems you are dealing with a long text of the abtract kind. You would be much better looking at the ideas in larger blocks and then rearranging them in Russian to make it for a more natural language. "find fulfilment" will never sound natural in Russian as there is no word of phrase specifically associated with such a construction (in all its uses). So you are aiming here for stilted language at best — and completely unnatural if you are unlucky to mess something up. However, in the longer paragraph it is much easier: you can use a more generic term in one sentence and then make the idea more specific and precise in the next one.
найти себя в чем-то (is short for "найти полноту самого себя в чем либо", "себя" in this case is "one's essence/fulfillment", полный-full)
example - найти себя в спорте (найти полноту самого себя в спорте)
well, whether you are fully filled with yourself then this you it is the one who you are.
Oсуществление comes close to the definition of fulfillment which is a realization (реализовать) of something.
He tries to find fulfillment in being perfect in his job.
Он пытается найти осуществление достигая совершенства в своей работе.
and
She tries to find fulfillment in cleaning the house until it looks polished.
Она пытается найти осуществление в уберание дома пока он не выгладит блестящий.
