> I'm a native English (Canadian) speaker and, given this context, would never pronounce "morph-y" as "morph why" (if that pronunciation was intended I'd capitalize the Y and probably not hyphenate it, "Morph Y").
Words conjoined with hyphens are always pronounced separately in normal usage -- the only exception I can think of is the special use case of hyphens representing continuations of a single word across a line break.
> Indeed, sometimes I'll use the -y construction when I'm inventing an adjective from a noun like this, especially if omitting it looks "wrong" to me because it's an invented word (not sure if I would've for "morphy" but whatever).
It's an "invented word" with or without the hyphen. But the standard way of "inventing" word forms in English is to apply suffixes directly to the root word without hyphens.
Using an interstitial hyphen as metadata to indicate one's own squeamishness about using a novel word form seems very strange to me. (The typical convention for this is to enclose the novel word in quotation marks, calling attention to the word itself in addition to invoking its meaning.)
> I don't know if you're a native speaker and there's some kind of cultural or generational gap here where some of us are more/less particular about this than others or if you're a non-native speaker trying to be helpful but underestimating the flexibility of casual written English.
I am very much a native speaker, and it's precisely for that reason that I find this nonstandard use of hyphenation jarring and disruptive of reading comprehension.
