Thanks for all the thoughtful responses; you've given me a lot to chew on! Trust when I say that I am the type to mull over things for quite some time before actually doing them, even for less serious endeavors than this.
For those curious, I am leaning heavily towards "no" on all three counts, though it pains me because they sound so promising on pfaf and lots of permie literature here and elsewhere. It's frustrating, but I wanted to say I do know the pain of dealing with invasives. Our property is thick with Siberian elm, non-native bush honeysuckle, and garlic mustard. Parks and nature reserves in the surrounding area are choked by buckthorn. We may already have the dreaded jumping worms. The three I asked about sound more desirable in comparison, I suppose. But I can't justify the risk of being the bad guy in any future story.
To further explain each temptation:
The pea shrub appealed to me as a perennial alternative to annual beans, with the protein and oil source giving a potential for greater food value than most fruit trees or shrubs. I sometimes think flippantly that the only reason they're not here is that the other baddies beat them to it. Anyway, tentative verdict is that it seems safer to just not muddle things further.
My first knowledge of autumn olive came from foraging blogs. I've even seen named cultivars sold on nursery websites, purported to bear sweet, tasty fruit. That's what I would have wanted them for: a hardy, self-sufficient fruit crop, with nitrogen fixing as a bonus. I'm thinking seaberries might answer both purposes with less moral dilemma.
I wanted the chufa as another of the rare protein and oil provider without much labor. I had even chosen a spot for it: a low-lying area near the house, which floods briefly in spring and gathers a puddle with every rainfall. It's even hemmed in on every side by the house and driveway. I thought that would control any rhizomatic spread, but reading about chufa's seed production... There are wetlands, lakes, and a major river nearby, so I just couldn't.
I just wanted to reiterate that I wouldn't take any risk to the ecosystem lightly. Perhaps on some level I simply wanted to be talked out of it, so thanks again.