Does the Ministry of Foreign Affairs (MFA) in Thailand only legalize documents translated into Thai for visa processing?

my recent experience.

Had a marriage certificate that needed MFA certification.

Step 1) my home country Embassy in Bangkok had to certify the original document first. Call you embassy and ask if they offer that service and what documents they need. Make sure you tell them it's for an MFA certification.

2) have it translated to English by an official translation services.

3) make an appointment with MFA online (they have offices in Bangkok, Chiang Mai, Pattaya, maybe more)

4) hand original document and translation to MFA for certification.

Takes about 2 business days.

Only the original will be chopped with an MFA stamp.

5) went to immigration, provided a copy of MFA certified original, and copy of translation. Original documents were requested for inspection by immigration officer and then immediately handed back to me for next year's use.

Here's the important point: MFA ONLY certify (stamp) the original document, not the translation. And their certification is ONLY to verify that the stamp of your Embassy is genuine. They don't certify the content, nor the translation.

Important. I needed my MFA certificate for Jomtien immigration, I went there before and asked if they require a translation to English and/or Thai. Answer: English only is fine.

So go ask your immigration office first, they may require a Thai translation.

MFA requires that the documents be translated to Thai before they are certified.

It is also important to note, that foreign documents generally need to be certified by the Thai Embassy in the issuing country. The requirements will vary by country, but typically you will need a certified copy of the document (certified at the national level) from the issuing country. Once you have the Thai Embassy Certification, you can then have the document translated and certified by the MFA. In this use case, it may not require the home country certification, but you would have to make that inquiry with the MFA or an agency.