What should my Ukrainian boyfriend do about his Non-Ed visa extension and transitioning to a Non-O visa in Thailand?

Hello everyone. I need some advice.

My boyfriend is a Ukrainian living in Thailand with a Non-Ed visa.

Recently, he just requested for extension with the reason of the war in Ukraine.

The immigration office gave a 15 days stamp for consideration. After the 15 days was due, the Imm said it is still not finished and need to come back later. But they can't tell, when. (I keep calling them for almost 2 weeks now but they don't know when. They are waiting too).

These are my questions;

1. If he gets this stamp after the day is already due, and gets an overstay stamp, how this will affect him?

2. We plan to marry this month and change to Non-O Visa. But we cannot send the document for translation to get marry (because we need to show his stamp that he has not less than 10 days left.). Does anybody know an option how we can change to Non-O visa?

Any other advice is all welcomed. Thank you in advance.

P.S. I am Thai