I think it’s about intent, not calories. If it’s for spiritual purposes and not insulin reduction, I don’t know if insulin should play a role in your decision. I think you could go either way, because this is about achieving something spiritual. I think praying on it would give you your answer! If bone broth works for you, do it! If it feels like it’s detracting from your experience, do a water fast.
From my personal experience:
I’m wearing a CGM (continuous glucose monitor) for several months now and have been doing IF and EF (everything between 16:8 to 8 days) some of the time. I like to drink a glass of organic vegetable broth (made from instant powder, contains no sugar) from time to time - without having any glucose response whatsoever. Zero.
I’m using one teaspoon, around 6 g = fat 1.5 g, carbs 1.8 g, protein 1.5 g.
So no, it does not break my fast, but since every metabolism is different, you have to decide and try for yourself. :)