I think the sentence sounds a bit clumsy (maybe because of the redundancy of talking about both an idea and theory, and the redundancy of using "field of").
I would prefer the following:
- What matters is how we translate the theory into practice.
- What matters is how we translate the idea into practice.
- What matters is how we execute the idea.
- What matters is how we put the idea into practice.
- What matters is to render the idea practicable.
- What matters is to render the idea into practice.
For whatever reason, "render" (when used with an object) appears to disallow proximity to the "from"-headed preposition, making the structure you ask about sound funny. For example, (1) seems fine but (2) seems marked.
- The translator rendered 'dog' into French.
- *The translator rendered 'dog' from English into French.
Interestingly, if you invert the prepositional phrases, it sounds better.
- The translator rendered 'dog' into French from English.
I'm not sure why this would be. But note that other change of state verbs (e.g. "change") also seem to favor a certain prepositional order:
- The witch changed John from a man into a pig.
- *The witch changed John into a pig from a man.
(4) sounds fine. (5) sounds a bit off.
One reason "render" might necessarily take the "into"-preposition before the "from"-preposition is that the "into"-preposition is what's called a complement of it, whereas the "from"-proposition is an optional adjunct. Complements of verbs always appear closer to the verbs than their adjuncts.