Welcome! An interesting set of observations. I rather suspect kakemoms' list ("
Overview of 6502-like cores, hard, soft, partial, overblown") would need to be updated, if definitive information could come to light.
256 bytes of RAM is physically rather large and would - to an approximation - double the cost of a chip. So it would only make sense in a microcontroller kind of product, to save having any external RAM. (I'm not sure when the term 'microcontroller' came into use.) Commodore might like to use such parts in peripherals, such as printers. But it would make no economic sense to add 64k of external RAM to a chip which has a very expensive 256 bytes already.
Numbering of parts is confusing: it will not be surprising to see the name number used for different parts, even though that goes against the grain. And as you note, a preliminary datasheet is only preliminary - the product might never appear, might be modified before appearing, or appear under a different name. A historian's eye is needed here.
Various teams like to decap and photograph chips: that will give a ground truth, including a measure of how physically large 256 bytes of RAM is, compared to a 6502 core. (If indeed such a chip has ever been photographed, or produced.)