Thanks, Bhante, for finding and sharing all these references!
As to the sense of ‘properly prepared’, in the Pāli Canon we find susaṅkhata (Snp1.2).
Baddhāsi bhisī susaṅkhatā
I bound a raft and made it well
We had a little discussion about the term saṅkhata and it’s translation ‘conditioned’ a few days ago, with my opinion being that ‘conditioned’ is not the best translation. It has connotations in English that don’t really apply, primarily that of “set prior requirements on (something) before it can occur or be done” (Oxford Languages Dictionary). The word ‘created’ you use in your paraphrasing of the Buddha’s response to the rituals, I think is more accurate.