Should my Austrian Magento store use Austrian-German variants (Jänner, Marille, Topfen)?

Yes, it’s a small touch with outsized trust impact. Austrian-German is the same written language as German but with hundreds of vocabulary differences that locals notice instantly. Common examples that matter in e-commerce:

• Jänner (not Januar) for January, appears in delivery date strings, sale-window banners.
• Feber (occasionally, not Februar), less common but used in formal contexts.
• Marille (not Aprikose), apricot. Critical for AT food / Heuriger-Weinhandel / preserve shops.
• Topfen (not Quark), curd cheese. Critical for AT food / bakery.
• Erdapfel (or Kartoffel; both used), potato. AT food shops use both.
• Sackerl (not Tüte), bag. Appears in cart UI strings.
• Schlagobers (not Schlagsahne), whipped cream.
• Heuer (not dieses Jahr), this year. Common in promotional copy.
• Servus + Grüß Gott, common greetings, the de_DE “Guten Tag” feels foreign to AT customers.

We add an Austrian-German locale override (custom de_AT translation file) on top of de_DE so storefront strings (cart, checkout, emails, transactional messages) all use AT vocabulary. Combined with .at domain + AT-hosted images + ATU validation, this signals “real Austrian shop” vs “German shop in disguise”.