Earlier quoted context omitted.
The Haxe community is made up of a lot of folks interested in general cross-platform dev, but there's also a ton of folks from the Flash diaspora. Accordingly, many tools and frameworks are evolutions of the "Flash way" (HaxeDevelop, OpenFL), while other tools and frameworks are starting from scratch, or adapting to other ecosystems (vscode-haxe, Kha). There's always been calls to "unify" the frameworks, tooling, etc…
HaxeDevelop isn't going to run on Linux or Mac, that's the point. Programming communities should focus on writing language servers and let developers use their favorite IDE instead of forcing people to use a specific IDE.
If you want a cross-OS IDE, or something that works on mac/linux, then use vscode + vshaxe.