I am feeding the kombucha today and will try some in a second ferment. As a rule I avoid any herb tea in the booch just in case, although I have tasted kombucha made with various herbs that seemed to come out just fine.
Second ferment, I have used things like lavender and ginger that are supposed to be antibacterial (or something) and they came out just fine. This time I'll put some cardamom pods in with some fruit and see what happens and report back in a few days.
As for veg ferments, you figure ferments with garlic and ginger (like kimchi) do okay with a pretty significant amount of them, might make things bitter or a bit slimey but won't be
enough to stop fermentation. I have had some odd results when mixing beets with other things, and at this point really don't mix anymore.
Maybe some of the other picklers might have ideas specifically to do with the smell.