"You have included content in your post that is not permitted."

Thanks for your response.

I did finally figure out on my own that the problem in my post was the material in Devanagari script; there was one other single character I didn't think to remove which continued to make it unpostable.

I did write to Apple Community Support ~24 hours ago, but there's been no response.

Meanwhile, our resident Multilinguist Tom Gewecke referred me to his note about the prohibition of Indic scripts (below). Funny that all the Brahmi-descended scripts (listed in Tom's note) are banned, but the Brahmi script itself is not. Maybe because the Brahmi doesn't include any complex conjunct characters? That's what makes Indic scripts difficult.

Could have saved me a lot of trouble and frustration if the red message had told me that.

𑀲𑀩𑁆𑀩𑁂 𑀲𑀢𑁆𑀢𑀸 𑀪𑀯𑀦𑁆𑀢𑀼 𑀲𑀼𑀔𑀺𑀢𑀢𑁆𑀢𑀸 

Sabbe sattā bhavantu sukhitattā 

May all beings be happy

PS: And now I'm told (in red): "Your post could not be saved. Please try again in a few moments." Maybe I've been signed out? Though the page still shows me as signed in. Log in again, try again.

Sinhala? It also has some complex consonant conjunctions. Quirk, indeed. 

From a National Geographic article on Sri Lanka: "Sinhala script, in the choice phrase of British writer Michael Watkins, looks like 'small plump circles ... all trying to enunciate the word "Coco."'"