I have similar craft tier 6 mod as well. It changes the crafting skill "craftingElectrician" max level to 200. Where working stuff mod maxes out the same skill at 100. I didn't expect that to create a conflict. But I took your advice and it got rid of that warning message. Nice find. Thanks.
Also Saminal, it appeared that I must have had the first version of you're A21 port of working stuff. Downloading it again fixed everything. By the way, did you intend to have the grills with a raging fire?
I found that these look nicer.
Charcoal Grill
<property name="ParticleName" value="chemistryStation"/>
<property name="ParticleOffset" value="-0.55,1.0,0.4"/>
Gas Grill
<property name="ParticleName" value="chemistryStation"/>
<property name="ParticleOffset" value="-0.55,1.1,0.35"/>
Let me know what you think?