Looks so good.

For the value structure I'd suggest you paint a test scale on a scrap piece of paper (or rather new canvas since this is digital) and make your darkest value (lowest height) as dark as you can whilst still retaining readability of the things down there. You may need to adjust the line work in that area darker in order to achieve this. I'm not sure if you started with a midtone background or not since when you digitized it you had one, but now it looks like you worked down from white. Which to me means there is perhaps just too much white, save white only for the highlights and go one tone down from white for the highest areas.