Thanks! I had a lot of fun writing it. I spent a week (maybe a little more) before the jam reading all the Inform 7 documentation to make sure I was limited by the capabilities of the engine rather than my knowledge of the engine.
I had a really hard time figuring out where to set the threshold for job offers. If I'd been able to get more playtesters I could have fine-tuned that a bit. However, it sounds like you played long enough to get an offer, which is what I was hoping for.
If you want to make sure you're getting the full experience, I have two recommendations. One, check out the action list in the help menu if you haven't already, and then try those actions with various items. As you said, items are modifiable, so you may get different results based on things like whether the item is wet, where the item is, etc. Two, figure out what the math is telling you, if you haven't already figured it out.
That thing you mentioned with the math is definitely a bug. The math should either give one or more correct responses, or the math should give an incorrect response. I just checked the code to confirm my suspicions: it's a misplaced else, so the incorrect message shows up in more situations than it should (but the correct messages show up only when they are supposed to).