@AlisdairM, your changes look good other than:

• Your wording changes to the \effect clause diverge a bit much from the paper. At the very least, this divergence should have been included with the initial commit comment and explained, but preferably, a change this great from the original wording should have been done in a separate commit.
• As Johel mentioned, you're missing the wording for \difficulty.
• The commit comments for changes which should have been included in the original commit (i.e. your fixes to what Johel found) should be prefixed with "FIXUP" so that the editor knows to squash these before merging. e.g. your "Update source/compatibility.tex" comments should have been something like "FIXUP: Add missing punctuation after "Uncommon".