It probably isn't the most ideal system, but its been that way for a long time, and I don't think we can change that for our site alone.
While there is a community process in place to undelete posts, as you alluded to, with less traffic to the site and also because you need 20,000 reputation to participate in undeleting posts, you seldom will get enough undelete votes - if ever (there are only 70 users on all of Arqade with that much reputation)...
I'll also say its made more difficult by the fact that there isn't an "undelete review queue", its all through the "moderator tools" only (the tools you unlock at 10,000 reputation), which if I am honest, even I barely look at, and I suspect the same from the other active users above 20,000 reputation (there aren't many really now-a-days).
What else can you do?
If you look at the Deleted Question FAQ that you linked to, there is a Meta SE post that goes into discussion of it, and the second most voted answer simply states the obvious - re-ask! In probably most cases on this site, this is probably the best course of action. The other and accepted answer to that post says:
If your question was deleted as abandoned, then not only was it unanswered but it also wasn't upvoted. Maybe that's because it's a super-obscure topic and few people even read it -- or maybe it means there is room for improvement in the question. The best course of action, then, is to edit to improve it and then request undeletion from users with the undelete privilege. On the sites I frequent, this is usually done via a request on meta.
IfAt least in the examples you linked to, I don't think an edit is needed in anyway. So that leads to the next point - if you really feel it should be undeleted, you can request so via a Meta post as well (using the undelete-request tag). I see nothing wrong with that. But keep in mind, it's entirely possible it can be automatically deleted once again (like a question I asked once was).