I wish you had given the GL of the NASB in your list.
If I recall it is about 5th to 6th grade, but I am probably very wrong.
That passage in Romans is 11.8. As a point of comparison, the ESV is 7.7.
You can look up the passage in both versions and I daresay you will not find one significantly easier to read than the other. The difference? How the versions use colons, commas and periods. The ESV uses shorter sentences, so it gets a lower score. The language, aside from punctuation, is very similar.
Look at Romans 8:3-4.
NASB: For what the Law could not do, weak as it was through the flesh, God did: sending His own Son in the likeness of sinful flesh and as an offering for sin, He condemned sin in the flesh, so that the requirement of the Law might be fulfilled in us, who do not walk according to the flesh but according to the Spirit.
That comes in at Grade Level 23.8.
Here's the ESV:
For God has done what the law, weakened by the flesh, could not do. By sending his own Son in the likeness of sinful flesh and for sin, he condemned sin in the flesh, in order that the righteous requirement of the law might be fulfilled in us, who walk not according to the flesh but according to the Spirit.
That's Grade Level 11.5
Both are formal English and, truthfully, the ESV is easier to read, but not on a factor of two.
For kicks again, I made a minor change to the NASB:
For what the Law could not do, weak as it was through the flesh, God did. By sending His own Son in the likeness of sinful flesh and as an offering for sin, He condemned sin in the flesh, so that the requirement of the Law might be fulfilled in us, who do not walk according to the flesh but according to the Spirit.
Guess what? The simple change of punctuation (replacing a colon with a period) lowered the score to 11.6, virtually identical to the ESV. (Although I like the ESV better stylistically.)