Hey man, I know something about QA testing as well. In my opinion, there aren't even that many bugs - it's just a visual novel after all and there aren't any new minigames coming so it is as you say. They just check bugs every morning and reopen them in the google sheet as not fixed or wherever they have them listed. And then it goes full circle...
For example this day today, there was an influx of 20 new bugs, they have been testing this visual novel for over a month now? And suddenly 20 issues popped up? By progress bar they haven't even added anything new. Therefore it is obvious that there is a number of bugs that they're trying to deal with but so far they cannot. It's not like coder is a pro, if he was he'd be working at a real company and wouldn't waste time doing commissions for porn game