Seems like an interesting effort. A developer is building an alternative Java-based backend to Lemmy’s Rust-based one, with the goal of building in a handful of different features. The dev is looking at using this compatibility to migrate their instance over to the new platform, while allowing the community to use their apps of choice.
Sure, anyone can pick up a new language or two over a weekend. That doesn’t mean they are confident enough to contribute to large scale programs with it. That takes much longer to learn.