I believe the reason the percentages behave that way is because I am casting between ints and floats, so some rounding is involved - I don't attempt to be more precise than a single percentage point with that display. Between 9 and 12, the difference of a single dose in the stack generally rounds to about 3%.
Stable describes a reasonably large range of sanity values, and the elixirs only restore a fairly small amount, so it's certainly possible that drinking a single dose of elixir near the top of the mask will push you over to focused, while drinking several containers of elixir near the bottom of the mask won't change the mask at all.
I do intend to be deliberately vague about the exact numerical values of the stats(which is why I use descriptions, not percentage bars or actual numbers), but it probably wouldn't hurt to make the masking intervals a bit more regular.
Drop rates aren't very balanced yet - there's an entirely new class of item that will fill the same loot niche as healing items and lamp fuel currently do, so expect both of those to become sparser in future releases. Also note that the most common type of loot container currently only generates items of those types, so you'll find more healing items and oil than equippable items in general.
I do intend to do a balancing pass eventually, but for now, I'm still working to add content, and I have quite a lot still planned, which is guaranteed to throw off any balance I try to establish now, so for the time being balance will be approximate at best =P
Once again, thanks for the feedback. I had a look at the error logs and I believe I can correct them both relatively quickly, so expect a patch release sometime tonight. I'm glad you had fun playing, and I hope you'll continue to check it out once in awhile.
Edit:
18 FEB 2019 - Alpha 0.9.6:
Handle repetition of invalid commands so as to completely cancel the repetition order. Level title moved to main screen, info retitled with [Detail]. Reworked borders for better consistency and more apparent focus. Reworked stat masks to scale better. Messages now scroll from the top of the window and are printed in proper order.
That should resolve all of the issues you raised, mihey1993. Thanks again for calling my attention to them.