Really low attenuation

[OldDogBrewing]

Have to ask, you are using a hydrometer and not a refractometer?

I'm using a refractometer, but I had to use the hydrometer too as I thought the readings were wrong hahaha but they were right

 

[OldDogBrewing]

I'm not sure any commercial beers are fully spontaneous in the sense of being fermented only with microbes from a coolship and not also from a barrel, dregs, commercial pitch, or some form of blending.

Full spontaneous is more of a home brewing novelty ...and frankly not a good method in my opinion, because a good Brett culture is needed to "fix" all the weird yeast and bacterial products. I rarely get Brett flavors from wild cultures, so pitching one is usually a requirement in my experience. YMMV.

Lambics rely on the barrels really, that way they have consistent micro flora
When they buy a new barrel, they will transfer beer from a known good barrel and infect it prior to using it with wort

So probably to have a good and complete micro flora you need a couple of captures, that's why I threw a piece of wood in there, if the beer is awful (mold, high butyric acid production, etc) I will burn the piece of wood, if it's something acceptable, I will add the wood to the next batch so I can build a good culture, this might take years but once you have it, you have an spontaneous culture forever, like lambic breweries do, then it will be time to infect other pieces of wood from the best beer and have them always in the fermentors, so with time there will be differences from piece of wood to piece of wood