Translation is the minimum. Depends on the immigration officer whom can ask for legalisation, or can skip it (usually when you come with your files translated in the first place).
Once they ask for it you should get it done.
From my country the full legalisation process here is :
Go to embassy in bkk with all documents that needs to be legalised, they don’t do it for every kind of documents but national diplomas yes.
You pay for 1St stamps.
Then you bring them to a translation shop appointed by the embassy.
You pay.
Then brings them back to embassy and pay again to legalise the Thai translation of your documents (not kidding).
Then, you can move on to the MRT office of the Thai foreign affairs ministry (check but I thing it is queen sirikit or klong Toei station) and ask for final Thai legalisation of your documents.
Then pay again but half cheaper than my embassy’s legalisation.
Takes time...
Your officer may or may not accept documents done halfway with just your embassy legalisation. I had both cases as documents accepted with only translated but not legalised documents.
I had my answer by another Way. Land border crossing open for goods (except eggs and masks) and for natives and some case for work permit. But not for people non natives that wants to get a visa 🙂
the visa agent of my company says that he could obtain an exception for me to get non B without exiting country if I were on Tourist visa but than I need to exit cause I was on ED and he’s not able to obtain the exception in that case.