Not sure The Interlocutor will ever read this; in the document you linked, right before section 1; you make the following (simplified) statement:

• An argument is valid if it has the property A and B:

1. If an argument has property A, it is valid.
2. If an argument has property B, it is valid and sound.

That contains a very obvious contradiction: you tell us there are two requirements for validity; then on the very next sentence you tell us there is only one requirement.

Also: the validity of an argument has nothing to do with the believability of its premises; your item #2 is a hot mess.