Sadly either you need to disable adaptive resistances, or you need to skip the target selection.
I am not able to change resistances at runtime. That is why I have to implement a prototype for each resistance value. In total, this results in around 600 different prototypes of biters/spitters with different resistances, which are then spawned according to the damage ledger.
That is why big-biter-fire-resistant-10 is a different target than big-biter-fire-resistant-20.
But ill have a look at it