Template imported successfully but document export with it fails

Source: Onboarding recap with Me Luzayisso (split from original recap).

Reported by: Danilo Schmidt — onboarding 2026-05-06 with Me Luzayisso (nl@etudeluzayisso.ch).

Issue: The template appeared as successfully imported, but it was impossible to export a document using it.

Needed: Repro steps + the actual template file (likely available from the customer).