Nice code!
If your primary reason is a search for web dev only, as you stated a few times, there sure are other tools to specifically fit your bill, code and object wise.
Each and every tool with its own problems as you shall discover, but coding is the art of going around

One main feature on GLB is its native support, so knowledge goes on as you switch tools.
GLB has a bootstart on html5, but it is limited on what its use can do in comparison with what GLB can do on other more native platforms.
The full GLB+html5 is still unknown to most of us, specially on the testing level.
I have seem some advanced users here doing nice stuff with it, not final projects, but ´demos´ that gets there.
By that I´m convinced that it works, how, is another question (that also includes the debugging framework you talked before and how to embend it on a page).
If you decide to stick around and put some time into it, we may all figure it out.
Otherwise, I heard some LUA based coding tools for html5 are ok, and some users here do so on multiple coding tools (and we all came from other tools(me=AMOS)) and they may be able to share more alternatives to your current case, as you probably saw on the off topic subject, where we once in while talk about newer/older dev tools.
Here is Albert´s post of html5 version of Wampu´s absolutely marvelous code:
https://dl.dropboxusercontent.com/u/292449/html5/Iso/isometricdemo.htmlOf course take a read on the original thread should you want:
http://www.glbasic.com/forum/index.php?topic=8152.0Cheers!
edit: be aware that this GLB html´s code is from april 2013...some configs in app may not be supported on today´s browsers as they constantly change stuff. Click on the red stripes to pull down configurations.
edit2: That rabbit hole you stated does not need to be that deep as looking into the 123´s source, surface testing GLB´s html5 stuff should do, but I think you may need the help of the more html5 coders here to boot should they be around.