Re-reading this sutta I sort of stuck on:
“And so, with an open and unenveloped heart, they develop a mind that’s full of radiance”
My reading is that the intent is something like “unconstrained” Ven Than. renders this:
“awareness open & unhampered”
I guess is that “apariyonaddhena” is translated in relation to the stanza context. I ended up thinking “unconstrained” instead perhaps due to my english English
“Unenveloped” seems a little odd to me but I am far, far, far from an expert.
Just thinking aloud, no disrespect to the infinitely more learned members here.