I suppose I find it concerning when you look at it from the lense of "long term, hard to notice effect caused by metal that is inherently fiendish/made with fiend's blood". I get the impression that the radiation-equivalent of the metal alloy, as designed, will not react to commonly used cure/heal spells and the like.
Kinda feels like a long-term trap, or preparing the field for harvest like the coins in Whiteharbor. But w/e. If you feel that holding a suspicious outlook with regard to fiend shit that we know the characters don't have a handle on, by dint of not understanding what process are going on or what the outputs of said processes do is fearmongering, to the point where it's not worth it to outsource a study into the matter, (before we make the tree, so that there are not hold-ups in our VS production, naturally) that's fair enough.