Which preservatives/additives in ingredients can interfere with kimchi-style fermentation? This is not yet about a problem, I am trying to avoid wasting time and ingredients or creating unsafe conditions while experimenting.

Many vegetarian recipes for kimchi and kimchi-style fermented food suggest adding soy sauces and other similar flavourings instead of fish and fish sauces.

The thing is: Many such condiments have benzoates or other preservatives added, and the purpose of at least some of these is ... being antimicrobial, and not in the same manner as acids or salt are, more in a "let's make the microbes get sick and die so you don't" manner...

Now, an antimicrobial compound, even if diluted, could probably interfere with a fermentation process, maybe even in an unsafe way (shifting the balance towards something harmful gaining the upper hand).

Are there known rule of thumbs what will and will not cause such problems?
Chlorinated tap water.

The effect on the ferment may be negligible, but I've never bothered to test it, lest there be unwanted putrefaction.

Boil the water that you're going to use to make your brine, then add salt and let cool.  The chlorine should volatilize at the boil.