I've gotten through a large portion of the content along the basic track of the game. The majority of it was already tested on a small scale, where I would test blocks of content as soon as I was done implementing it so major stops and issues were already caught early, however, I never actually tested everything together in one long run. That made things easier in some ways, since the big stuff like combat and cutscenes don't need much if any tinkering with and I can just make sure I gauged progression properly so only small difficulty tweaks are needed where I aimed a little low or a little high. It made things harder and more tedious, as expected, in others. It's revealed a lot of small things that would stop any normal playthrough; doors not being hooked up so you can't enter an area, but you could leave it because I tested the inside at the time I made it but missed hooking up the outside, is one of the big ones. Javascript being Javascript and the annoyance that come with that is an entire other issue, and one that makes me think I might have been better off using an older version of RPG Maker that didn't use it.
It's still going to be another few weeks before I'm done testing as much of it as I can, as I only have so much time outside of work among all the other things I'd like to do. At that point I can see how many of the challenge fights I want to implement before releasing the base game and then moving towards the extra stuff.