These are from the collection called
Thus Spoke Kishibe Rohan by Hirohiko Araki. In these stories Rohan (a Part 4 character) isn't really the main character for most, just an arbiter there to see the story happen. I wonder if Rohan is a popular character in Japan, he seems to have a lot of side stories. He's definitely one of my favorite JoJo characters.
At a Confessional
Really good short story. Rohan takes a trip to Italy for reference purposes, and ends up in a Church accidentally in the confessional on the Priest's side, where he hears a confession from a man about how he was cursed to suffer misfortune in his happiest moment.
Mutsukabezaka
Another really good short story, this time about a woman who accidentally kills her lover, and his wound never stops bleeding, with Rohan's investigation into it as a Yokai.
Well, two minor part 4 Villains show up in this so I guess this collection isn't canon either. Weird.
Village of Millionaires
KISHIBE ROHAN DON'T GIVE A FUCK 'BOUT DAT
Another good story about a completely secluded village of millionaires and a lesson in manners.
Poaching Reef
Decent story about Tonio and Rohan going poaching for a rare creature.
Nice to see Tonio. Always thought he deserved a spinoff, but I think he might have an LN one. Josuke, Koichi and Okuyasu briefly show up too.
Mochizuki Family's Moon Viewing
A family who stays together to watch the Harvest Moon together due to an apparent curse of their family dying on that day and THE MOST TERRIFYING STAND OF ALL TIME JESUS CHRIST
Well I guess that's all of the manga side stories I know of. I already read Rohan at the Louvre a while ago and Purple Haze Feedback is an LN.
I guess I'll just have to keep hoping for that Jorge Joestar translation.
It's pretty interesting how you (or I can at least) tell what time these were all done at by the artstyle since Araki's had so many drastic changes over the years.
If you're a JoJo fan I would recommend these, and even if not some of these are just good oneshots.