Concerns: pushword/static-generator
Only affects statically generated sites with more than one locale. The per-locale 404.html files were already generated but never served: every error got the default-locale page. The next pw:static run now also emits one three-line .htaccess per extra locale folder (scoped ErrorDocuments, overriding the root ones for /{locale}/…), and the generated .Caddyfile rewrites errors to the localized file by URL prefix.
Nothing to do — unless you override Caddyfile.twig, whose handle_errors block now reads an extra_locales variable; copy the new block to get the same behaviour.