I thought I would offer my recent experience. From UK, I applied for my SETV on the correct Thai e-Visa website.
The first one was rejected because I did not check what I had typed correctly and had put an extra A next to my name confirming that was the name as in my passport.
Eg. I typed, John Alan A Smith instead of John Alan Smith.
The email I received from them in red capital letters stating I had to redo the visa application and no money will be refunded. £30 down.
I re-submitted my application checking it thoroughly and submitted it.
It was rejected because in the photograph I had a jacket on which covered the shape of my shoulders. So I had to do another one attaching a photograph of my naked shoulder which they accepted. However......
Even though this is not a requirement/question on the application, they wanted photo ID of the person who is accepting me into their home in Thailand (private home not a hotel or condominium)
So I had to get them to send me a via WhatsApp a photo of their ID.
Finally everything was accepted but annoyingly it cost me £60.
Here's the thing though. I think I could have altered or amended the first application but there was a message in bold red letters saying the visa was rejected and I had to submit another visa. In hindsight I think this was badly worded and I may have been able to amend it rather than scrap it and start another one.
So my advice is this. Check everything, check it again, then check it again and get someone to check it again 😁
If it is rejected and you get the bright red bold messages saying it has been rejected and you have to do another visa, try editing it and save yourself stress and money .