So... section = group, and row = position in that group. For your example, I'd imagine that you'd be looking at something like "goodtask3://view?section=3&row=1"?
I don't think spacers count for anything, so everything before your first group title counts as section 1, and each group under a title counts as another section after that.
Far as I can gather, if you feed GoodTask a path or section/row location that doesn't actually exist, it defaults to the first list in your sidebar, which might explain why you were getting your inbox when you asked for section 5— from what I can see of the image you've supplied, it looks like you've only got 3 sections...