Okay, let me clarify.
>I've had the same 6 environments out for months now, and had (for example) 18 Peak objects in the Meadow section, so I should be expecting a Nosepass to appear. Two months later, no Nosepass, but apparently the blocks are being detected with a 1x multiplier, since I get Geodudes at level 45 like I'm supposed to.
You're supposed to be getting a Nosepass. The rate of appearance is unknown, so you're probably getting unlucky or something like that. Keep on searching. And make sure you're encountering Wild Pokemon in the Grass.
>How does one know if the blocks are being upgraded? Is Baoba supposed to call and tell you, and if so at what time, because I've never received a call from him?
I don't know how to explain this, so I'll post Bulbpedia's take on it:
"Each area of the Safari Zone keeps a hidden count of how many days it has been used. Every ten days of use, a certain block type will be upgraded just for that area, and Baoba will call to notify the player of this. Once a block for a certain area is upgraded, the upgrade will not disappear if the player moves the area or takes away the blocks. When blocks are upgraded, they increase effectiveness. For example, a Plains block with no upgrades would count as one Plains block, but a Plains block with one upgrade would count as two Plains blocks. So, after 20 days of use, a particular zone's Plains and Forest blocks would each be worth 2, while the Peak and Waterside blocks would still be worth 1." ~Bulbapedia
>When Serebii.net says 18 Peak objects for 30 days, does that mean 30 x 24 hours real-time, or 30 x 24 hours in-game time, or does midnight have to strike on the clock 30 times (23:59 -> 0:00)?
It means 30 days in real life time. Remember that the DS has an internal clock in it, and the game uses that for the time also.