So, the words I definitely didn't remember while in bed too late at night: Tremorgenic mycotoxins. Please note that I am in no way an expert in any of this, but as a fellow dog-owner I got very cautious when I read about someone actually losing a dog which ate from a compost pile. I found a source (link below) which highlights a few points, amongst this one that might be important:

"Mold growth, particularly Penicillium mold, and production of mycotoxins in food (walnuts, dairy products, pasta), animal feed, or food waste (compost) can result in tremorgenic toxin production. "

My compost pile definitely contains some of the above, but a pure garden waste based pile might not.

Another point worth highlighting as 'vomiting' is mentioned in this thread:

"After ingestion, the onset of clinical signs can occur in a few hours. Toxins ingested in lower concentrations appear to cause fine muscle tremors lasting for hours to days, whereas large tremorgenic toxin ingestions can cause seizures and death. Vomiting can be the first clinical sign and may help limit the severity of the intoxication. "

I suppose the size of the dog and the amount they ate from a pile all come into play here. Again, I am by no means an expert on any of this, just a (overly?) concerned dog owner. Please correct me if I'm wrong on any of this, and enlighten us all. If we promote composting in this community, and there is any danger to any member of your household whatsoever, I feel we should inform people and err on the side of caution.

https://www.msdvetmanual.com/toxicology/mycotoxicoses/tremorgenic-neuromycotoxicosis-in-dogs