Never gardened where we could have persimmons, but as a kid we hunted every year on a friends ranch in Northern California that had some persimmon trees on it. Grandpa had a tree or two, also.
Bottom line, I learned that persimmons are not ripe for eating, or jam making, until they hit the soft & gooey stage AFTER a hard frost or two. Frost doesn’t ripen them, but they take so long to ripen that they are not ripe before the frosts hit.
We are doomed then, the persimmons here are long gone before frost usually.
There are 2 types of Persimmons, the pointed bottom Hachiya which can be very astringent tasting if not ripe and the Asian Fuyu flat shaped that can be eaten when firm. Pick the Hachiya late in the season and store it and place a few in a window sill to soften to eat and you can also freeze a few and thaw them one at a time to speedup the flavor, but this depends on how ripe they were when you picked them. They Fuyu have the texture of a crunch Pear.