The vagueness in some points really is a problem. For example AS seems to support two different ways of transporting comments. The first one is the one used by OStatus. Means: The commenter just transport the own comment to the own followers (which will lead to incomplete threads). And the second one is the one that Friendica and Diaspora are using: The thread owner relays the comment to the own followers. For this you need just another standard that is only mentioned in a half sentence in the specification.

Additionally the current specification doesn't allow private messages like we know in Friendica and Diaspora. It only knows content that is only visible to some persons (like we also support). It's like with pump.io which doesn't have support for this as well.

So when we want to implement AS, we have to leave the standard. There is an issue that covers this - but it hadn't come to a final (single) conclusion but two different (incompatible) ways to solve the problem.