| Tone diacritics dropped or set wrong | The tone marks decide the word: ma (ghost), má (cheek), mà (but), mả (grave), mã (horse/code), mạ (rice seedling). A missing mark turns one word into another — on a certificate, a different name. | Native speakers set every tone and vowel mark correctly and translate the meaning, not the diacritic-free string of letters. |
| Encoding destroys characters | Vietnamese stacks diacritics (ế, ữ, ậ) and has special letters (đ/Đ, ơ, ư). Old encodings (VNI, TCVN) or mixed Unicode forms produce question marks, boxes or shifted accents — the file becomes unusable. | We work throughout in Unicode (NFC), verify the normalisation and confirm the correct rendering of đ/Đ and stacked diacritics in the finished PDF. |
| Name order reversed in form fields | Vietnamese puts the family name first and the given name last (Nguyễn Văn An → family name Nguyễn, given name An). Forced into German "first name / surname" fields, the person officially becomes someone else. | We map family, middle and given names to the target fields exactly as in the passport and document the mapping where there is any doubt. |
| Syllables joined or split wrongly | Each syllable is written separately (Hà Nội, Việt Nam). Joined up on a German pattern, or "anglicised", place and personal names diverge from the official spelling. | We keep the syllable-by-syllable writing and the official form of place and personal names exactly. |
| Northern / southern variety not fixed | Northern (Hanoi) and southern (Saigon) vocabulary differ in everyday terms; a variety chosen for the wrong audience reads as foreign or ambiguous. | For official texts we use the supra-regional standard; where audience matters, we fix northern or southern in advance and keep it consistent. |
| Grammar "translated" 1:1 | Vietnamese does not inflect: no verb conjugation, no cases. Tense comes from particles (đã, đang, sẽ) and quantities need classifiers. Carry German forms over one-to-one and you produce wrong or unnatural sentences. | Native speakers build tense, number and reference through particles, word order and the right classifiers — idiomatic, not literal. |
| Register missed (Hán-Việt vs. native) | For formal, legal and technical terms Vietnamese uses Sino-Vietnamese vocabulary (Hán-Việt); everyday speech uses native words. The wrong layer on a certificate sounds casual or ambiguous. | Professional translators choose the right word layer for the text type and lock the terminology through a maintained term base. |