The languages you already finished come across as published, and cost nothing to bring.
Translate & Adapt stores its translations in Shopify's own translation layer — the same place Lingomatic reads from and writes to. Your work is already where we need it, so moving over is an import, not a re-translation.
The import only looks at languages you have added as targets. During onboarding you choose languages before the first sync runs, so the default path already covers it.
If you added Lingomatic earlier and are only now adding a language you had translated in Translate & Adapt, add it in Settings → Languages and run a sync. The import runs again and is safe to repeat — it never touches a translation you already have.
Lingomatic reads your store's content, then reads the translations Shopify already holds for each of your languages. Everything it can match arrives as Published, word for word as you left it, live on your storefront the whole time.
This works for any app that stored its translations natively in Shopify, not only Translate & Adapt.
Nothing. An import is a copy: no model runs, so no credits are spent. Check your balance before and after the first sync — it will be the same number.
Imported languages also stay out of your plan's product allowance. If your plan covers 100 products and two languages arrived by import, you still have the full 100 products of room for the languages you add next.
Translations are stored per language, so adding one only ever writes rows for that new language. The two you brought with you are not read, rewritten, re-translated, or charged for. Set your brand voice and glossary before you translate the new one — they shape the new language without disturbing the old ones.
Two things, both of them yours to trigger:
Nothing else re-translates an import. Leave it alone and it stays as it is, indefinitely.
After the first sync, open Translations and look at the coverage per language. Anything showing as untranslated did not match, and is worth a look before you start a large job.
See also: Understanding credits · Your translations are yours