The code for Growth campaign landing pages (see T284740: Account creation: design an enhanced account creation landing page and various related tasks) is a mess of hardcoded content and behavior for various specific campaigns; every small modification requires a code change (and usually a backport and a slow scap sync-world). It should have some sort of template system so that new campaigns only require configuration to set up, with i18n handled via on-wiki system message overrides. This would also make it possible for the communities to set up their own campaigns without Growth team assistance.
See also T305443: Account creation: remove GLAM event ad-hoc code after 20th of April which is closely related.