Hello Brice-
It looks like your project is coming along nicely, well done! Everything you've provided so far looks good: your carousel has items and flipper events, and your slide has an MPFCarousel node with children with names matching the selectable items. And you say that when you go to hero_select mode, that slide shows up correctly but just doesn't rotate?
My first idea is to double-check that the MPFCarousel node has the "Carousel Name" property set to "hero_select" so that it knows which carousel's events it will respond to.
After that, perhaps the logs will shed some insight. Again your mode config looks all correct so I would expect to see item_highlighted events in your MPF log that have the right carousel and item values, but it's best to double-check. And in the GMC logs there shouldn't be any warnings or errors. Both MPF and GMC write their logs to files (MPF in your project /logs folder, Godot in the Project > Open User Data Folder), but they also write output in the terminal/editor window so you can see it quickly.
If all that's correct, you can try debugging the MPFCarousel node itself by adding an MPFLogger node to the slide, attaching the MPFCarouselNode as a logger, and setting the log level to Debug. If nothing jumps out immediately, please share your MPF and GMC log files here and we can keep investigating!
-Anthony