When using the script

var brushTransformer = creosotebrush.transformCustom("brush/uses", (item) => {
if (item.damage < 4) {
return item.withDamage(item.damage - 1);
}
return brush;
});

craftingTable.addShapeless("test", treatedplanks, [brushTransformer]);

The item transformer will work, reducing durability until there is more than 4 damage, at which point it replaces it with a different item. I was wondering if it could be made compatible with the item_application recipetype. I ask because while it works in a crafting table, if you look at the script below, it will just keep damaging the item and never return a normal brush when a certain amount of damage is reached.

recipetype:create:item_application.addRecipe("wood/planks/treating", [treatedplanks], tag:items:minecraft:planks, brushTransformer);

I can't say I'm exactly sure why this happens or how it would be changed, but just wondering if the mod could be changed to allow this.

Unfortunately this is not possible as create does not call the methods that item transformers require to be done.