> For example, open an iMessage text and paste one or more images.

I never until today thought of pasting images. I always add them using the Photos button, then just write my message as normal.

I see now how moving cursor around rich text with embedded objects is glitchy, and I imagine if you deal with that on daily basis it could be frustrating.

However, none of the other issues you or others described seem to be reproducible on my phone. Double-tap to select, or tap to place cursor, seem to just work in regular plain text areas.