There is a doc that lays them out, but it appears to be out of date, from this thread it's pretty much this:

• Application Not Made -> You didn't submit your application yet, you need to check the box to the left of the application and then click the orange "[ Application >" arrow on the bottom right of the application list to actually submit it.
• Temporarily Received -> You've successfully submitted it, there will be an OK next to it saying the basic check has been completed
• Accepted -> It's been accepted and moved in to the queue for someone to verify it, this took me about 12 hours to see the change, i would suspect yours will change in a few hours.
• Examined and Passed -> It's pending issue
• Ready for Issuance -> should be quick (thanks sensei )
• Issued -> You have an eVisa, and you should have an expiration date showing up as well. Soon after this you should be able to download the eVisa, though I've heard you need to be able to pull it up on your phone at the Japanese airport as it has a rotating QR code that needs to be refreshed.
• Withdrawal Requested -> You requested it to be withdrawn to fix an issue they alerted you about, like no middle name.
• Withdrawn -> The withdrawal has been completed, this takes about 12 to 24 hours in my experience.

The "issued" status I'm not 100% sure on, and don't know if there's anything in between. When mine got kicked back to me, it was in the Accepted phase still and I was told to withdraw it. So if you get past accepted to Examined and Passed, you should be good to go.