Regarding horseradish:
I think one has to carefully differentiate between an actual mesorah to do something (or not to do something) and something which may have been done “unwillingly” or something that was done without any halachic significance. For instance if in Europe they bathed on during the day (let’s say because it was cold at night), I think we can all agree that this hardly constitutes a mesorah to bathe during the day and not at night. So when we see that certain vegetables were used, we have to determine if they SPECIFICALLY used these vegetables or perhaps they simply didn’t have or couldn’t afford other vegetables. The result would be that perhaps horseradish is ok bedieved or even that it’s not ok at all. But simply responding “mesorah” might not address the issue.
This reminds me of Techeiles where people say that it’s against the mesorah. But there was never a mesorah to not wear Techeiles; it was just something that was unable to be done.