It's definitely uncertain territory whenever you're ingesting a seldom-sampled plant species and even specimen you don't know very well.
I think there's an amount of risk even consuming samples of say shredded Acacia confusa bark collected from an unknown source. Certainly there are more reputable suppliers, which I wouldn't feel nervous about, but there's always the potential for a mis-ID'd tree and random plant debris entering into the equation, not even considering the energy the person collecting puts into the material. I for one feel that the collector imprints something onto the material, and I've heard the Mazatecs are very selective about where their medicine comes from.
This is why I've really preferred ingesting plants and mushrooms I've grown myself.
Even in the case of the recent interest with Elaeagnus spp. I've been a little reluctant to sample it simply because of the question "what else is in there besides the alkaloids I'm after?" In the case of Elaeagnus there's recorded use by traditional healers, so I wouldn't be as nervous as with some other things, but also with this genus I'm not so sure about the alkaloids in it anyway
People have been testing plants for a long time without knowing all the minor details of how it influences us. You can do in-depth chemical analysis and you can use the old method of upping your doses little by little. Even a little strychnine won't hurt you till you hit a certain point. But in the case of little bits of aminitin, it seems you might easily miss the warning signs which take some time to present themselves. Mushrooms seem to me more tricky than plants a lot of the time though.
I have been thinking about taking harmalas and making a brew of Big Medicine or AQ1 phalaris, and slowly titrating up my phalaris to see how it is... but thinking about it now seems like one of those awful experiments I dream up that end up leaving me regretful and sick in some way...
I wonder how Johnny Appleseed did work with phalaris, I heard he was using phalaris or its extract orally in the 90s.
It's these unknowns that make one yearn for some good cubensis, cactus, and better known friends