After reading about problems with this online TM30 reporting, I was expecting the same but No.
We'd been registered on the old system although we'd never used it but have had to re-register now.
I set it up using my wife's details - ID card, blue book etc. - and in English. She knew what I was doing, of course, but took no part in it. It's far easier for me to complete everything in English than for her to do it in Thai. I then downloaded the example Excel sheet, completed it and sent it off. There were small problems caused by my unfamiliarity with the website but nothing that couldn't be sorted in a couple of minutes.
Only thing I didn't like about it was that I couldn't submit in advance of the arrival date, despite knowing all the details.
Once the report had been submitted, I took a screenshot of the webpage, including details of the person staying with us, and that was it - finished.
I suppose it took about 30 minutes in all.