I currently build my own Modpack and fund that i can create and remove new Recipes without a problem, but replaceOutput has no effect on the Mekanism recepies, since it only creates its own ingots when smelting but not the Type i defined.

The following lines Work without a problem in every other Recepie i fund exept Mekanism and TConstruct

event.replaceOutput({}, "mekanism:ingot_copper", "tconstruct:copper_ingot");
event.replaceOutput({}, "#forge:ingot/copper", "tconstruct:copper_ingot");

PS: I use TConstruct and like to Only get TContstruct ingots since Tconstruct is its own hell to change in any way