Meaning of the Rooted Sutta
This is what Sujato has to say;


  No, “gain a footing” is incorrect. Amatogadha is a common term,
  frequently used alongside amatapariyosāna and amataparāyana in the
  sense of ‘culminate, climax, finish’.
  
  The basic meaning of ogadha is to be grounded or gain a footing, but
  here it clearly has an idiomatic sense. I think the root of the
  metaphor may lie with a boat crossing a river: when it reaches the far
  shore (parāyana) it is beached or grounded. Perhaps we could translate
  something like “gains a safe harbor in the deathless”.


Which is imho not much of substantiation.

As for your inquiry it is somewhat noteworthy that 8 out of 10 points from 10.58 appear in AN 8.83 (which covers the first eight of the ten questions), commentary to the Sutta has it that "all phenomena" (sabbe dhamma) there means the five aggregates. This is important because it comes into play when people express their interpretations where some might say that sabbe dhamma refers to only "wholesome qualities" for example, this has happened.

This is not the only place where this disagreement between translators plays out, there is also AN7.48 wherein the amatogadhā amatapariyosānā occurs as well as sn48.44. It is the same disagreement however if one looks at Bodhi's translations one will see that he has previously translated amatogadha as footing for sn48.44.