I can't find any statement to this effect by Jean-Marie Schaeffer, but it seems to me that the English verbs that best correspond to "sustanciar" and "objetivar" and "actualize" and "objectify". "Materialize" is also a possibility for "sustanciar", but "actualize" seems better to me, and "actualize" or "actualization" seem to occur in texts that discuss Schaeffer.

As Bea has shown, "sustanciar" means "llevar a cabo y hacer material un proyecto, una idea o un sentimiento". "Actualize" means:

"Make a reality of.
‘he had actualized his dream and achieved the world record’"
https://www.lexico.com/en/definition/actualize

"To realize in action or make real"
https://www.ahdictionary.com/word/search.html?q=actualize

You could say "impulse towards actrualization and objectification", or "actualizing and objectifying impulse", but I think it flows best with simple verbs and the meaning's the same.

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Note added at 1 hr (2019-07-10 21:28:04 GMT)
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I meant to write: 'the English verbs that best correspond to "sustanciar" and "objetivar" ARE "actualize" and "objectify".