Is there a low tyramine substitute for tamari?
As unpalatable as it might sound: Pure MSG would be umami with the least added compounds :) A very glutamate-rich (but natural) broth can be made from kombu seaweed (but keep in mind it can have an obscene amount of iodine, which could be relevant in your case.)

Distilled vinegars (or non-brewed condiment) will likely contain less amines or amino acids.