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.