How do I configure BTW / TVA / MwSt trilingual invoice templates per store view?

Belgium calls VAT three things depending on the buyer’s language: BTW (Belasting over de Toegevoegde Waarde, Dutch), TVA (Taxe sur la Valeur Ajoutée, French), MwSt (Mehrwertsteuer, German). Rates:

• 21%, standard rate (most goods + services).
• 12%, reduced (some agriculture, social housing, restaurants).
• 6%, reduced (essential food, books, water, pharmaceuticals).
• 0%, B2B intra-EU sales with valid VIES BTW number (reverse charge); newspapers + journals.

Magento configuration:

1. Tax classes, create BTW-21, BTW-12, BTW-6, BTW-0 in Stores → Tax Zones & Rates.
2. Tax rules per rate, scoped to BE destination.
3. Invoice templates per store view, override the default sales email + PDF invoice template:
   • be_nl view → “BTW”, “Btw-nummer”, Dutch invoice copy.
   • be_fr view → “TVA”, “Numéro de TVA”, French invoice copy.
   • be_de view → “MwSt”, “USt-IdNr.”, German invoice copy.
4. Buyer-language fallback, if a Dutch-speaking buyer orders on the FR store, optionally send the invoice + auto-reply in their preferred language (configurable per customer).
5. BTW intracom validation on B2B checkout via VIES, required for 0% intra-EU reverse charge.