A major update!
Going back to the decompiled SCI0 system scripts and comparing them with their SCI01 counterparts using ExamDiff, I have managed to fill in the blanks for nearly every system script. The temp variables and parameters have been identified.
I'd gotten this idea from my recent decompilations of the LSL1, LSL5, SQ1VGA, and PQ3 demos, where I took the extra step in painstakingly identifying all the params and temps I could in their system scripts.
Also, while I'd done this earlier, I'd also created a subclass of InvItem in the main script. This subclass will allow item descriptions to be placed in a Text resource, saving on heap space and simplifying potential translations.
And there you go, the definitive template for SCI parser games is just about complete!
To answer Doan Sephim's question: The reason you see duplicate resources may be because I set the template to be managed as patch files. This is for source control purposes. The interpreter prioritizes patch files over the contents of RESOURCE.000. I have been using Kawa's SCICompanion build.