The easiest way is, if both of you have signed the CLA, then one of you can create a pull request, without causing licensing problems.
Everything else makes it more complicated, to keep the project “clean”. We probably can’t “merge” PRs that aren’t clear, what’s intended by the author.
Fixing typos will not create any problems. Where things will get complicated start with eg: “fair use” [1] … First of all it’s an areal law. So it’s not applicable all over the world.
… Avoiding such complications is easy. We use a CLA and 2 open source licenses. BSD 3 clause for the code and Creative Commons Attribution 3.0 [2] for prose text.
[1] Fair use - Wikipedia
[2] Deed - Attribution 3.0 Unported - Creative Commons