Do Pilot and Pioneer's train cars meddle in their love lives like their fellow engines, or is it not done?
Pioneer's do not. 505 and 570 have known him their entire careers and while his obliviousness to other engines' overtures is frustrating, their sense of coach decorum prevents them from saying anything lest they embarrass him. They figure that if it was going to happen for him, it would have by now and that maybe their engine just isn't interested.
But what do they know? They're articulated so they never really had anyone but each other. They're not the best judge of these things.
Pilot's cars, on the other hand, are a mixed lot. While Pioneer's cars observe a more staid, old-fashioned car etiquette, the Nebraska Zephyr is more outspoken and takes liberties with their duties.
Those at the center of the train do not meddle however. Vesta doesn't because she likes yard drama and it drives everyone else insane that Pilot is uncoupled despite being spoiled for choice. Minerva thinks it is not a car's place to meddle in the affairs of their engine. And Ceres would have to speak up to meddle so that's right out.
Venus and Juno, however, do. They're not overt about it; they know a gentle ride is preferable, but they do nonetheless shunt as much as they can.
Juno is the observation car and so she observes. It seems quite obvious to her that the two Zephyr engines ought be a paired set, particularly once Pioneer starts actually visiting and it'd be more than just letters.
Venus is a little more self-serving in her efforts, if only because she might have thought she and Pilot would have been the It Couple in the museum. Once he cleaned up, that is. That Pilot completely failed to recognize that... well, if she can't have him, someone should. And if it's the Pioneer Zephyr, all the better. (She is the opposite of Mate: If it's Pioneer, then she didn't strike out, she just couldn't compare to the engine in the letters, that's all!)