Try searching for your new items by code name, not localization name.
			So resourceEssenceFireBundle instead of Fire Essence Bundle.
			Narrows down if it's a bad item or bad localization. You can do the same in creative.
		
		
	 
Hmm, not sure how to put this without @%$#ing you off, erm, you did read the code right? not just see the titles of the files I appended to?
Why do I say that, well...
<config>
<!-- Patch to Sorcerer and SorceryCompatibilityDF mods -->
  	<!-- ALL: resourceEssence increase stack size from 5000 to 6000 -->
	<set xpath="//item[starts-with(@name, 'resourceEssence') and not(contains(@name, 'Bundle'))]/property[@name='Stacknumber']/@value">6000</set>
	<append xpath="/items" >
		<item name="resourceEssenceFireBundle">
			<property name="Extends" value="resourceRockSmallBundle"/>
			<property name="CustomIcon" value="resourceEssenceFire"/>
			<property class="Action0">
				<property name="Create_item" value="resourceEssenceFire"/>
				<property name="Create_item_count" value="6000"/>
			</property>
		</item>
  	</append>
</config>
	and...
<configs>
<!-- Patch to Sorcerer and SorceryCompatibilityDF mods -->
	<!-- ALL: resourceEssence allow stacks to be made -->
	<append xpath="/recipes">
		<recipe name="resourceEssenceFireBundle" count="1" craft_time="10" craft_exp_gain="0">
			<ingredient name="resourceEssenceFire" count="6000"/>
		</recipe>
	</append>
</configs>
	Those are snippets from the post.
I'll be taking a second look at this later today, since I seem to be learning daily new things about how xml is used with 7D2D.
Ta