In section 4 "Keyframes", the specification says:

At the 1s mark, the slide-right animation will have the same state as if we had defined the 50% rule like this:

The words "At the 1s mark" seem to imply that the rest of this sentence is only true for the 50% mark. I think the example wants to say something different though, which should rather be worded like this:

The slide-right animation will have the same state as if the 50% rule were defined like this:

Or, even shorter:

The two 50% rules from above can also be combined into an equivalent single rule:

This wording change intentionally omits the word "we". That word should not appear in a technical specification because every occurrence of "we" must clearly define who exactly is that "we". The word "we" occurs a second time in the specification, in example 7.

In the second part of example 3, the to rule is repeated from the first part, but not the from rule. This is confusing because repeating the to rule doesn't change anything about the 1s mark. Also, the introduction for the second part only talks about "the 50% rules". Therefore, if the second part of the example is equally valid with the to rule removed, it should be made shorter. Either that, or the from rule should be added in the second part of the example, for symmetry.