A couple of translation suggestions:
Page 15: Seishunki is a concept (the idealized version of youth) rather than a thing (simply youth) so he's saying more about not wanting ruin the springtime of his youth with rash actions. How to parse that into a useable translation is admittedly tough.
Page 20: Fukuki says kisha (汽車) to refer to a train, but that's a somewhat anachronistic term used for a steam train, the first Kanji being that of "steam." J.R. is Japan Rail and they use electric train so that's why Tsubasa was confused. It's apparently the local usage in Hokkaido. I think in the rest of Japan, some old people are still stuck on kisha, but for most people, that brings up the image of black iron beasts burning coal spewing smoke.
Page 21: Top left panel: The translation should be more like, "A lot of people go shopping for clothes there, but plenty of people like to wander around on a date, sampling different food."
Page 22: Tsubasa says "Doero" and from the context, he's talking about the situation where people visit each other homes being very (do-) erotic (ero) rather than him being turned on, which he may very well be. In his head, he's imagining boys and girls being alone at home with no supervision (since he comes from Tokyo where both parents working is more common and the house is empty during the day). Either works, more or less, but I think it's closer to the first.
More on page 22, the bottom right panel: Tsubasa is saying, "There are so many options on what to do, but guys in the city would rather pick going to the house first" for the foregoing reason I stated. For them, going home together to an empty house with your gf = sexy time. Here we see the foundation of a profound misunderstanding and shenanigans. The current translation actually gives a wrong impression on Tsubasa's dating experience. In the last bubble, "tabun" is closer to "probably" so it makes it clear that he's guessing what everyone would rather do and not just comparing it to his experience.