I think it’s more probable that it would have solve the easier problems first, rather than some hard and only some easier; although that is supposition.
Reading this thread and the blog post gives more idea about what the problems might involve.
It’s difficult to judge without more information on the actual results, but that means we cannot draw any strong conclusions either way on what this means.
1. it suggests it’s possible that more of the problems are IMO-esque than previously thought, we don’t know how the share of solved problems is.
2. calling IMO problems “well known undergraduate problems” is a bit much