My CPDN Pending Credits seems to match the credits that are reported on the stats site (http://boincstats.com/en/stats/2/user/detail/724503), so it leads me to believe that Pending aren't really pending, but instead are actual granted credits. Can anyone confirm this?

The pending credits are not used on CPDN. Models here are much shorter than they used to be (by popular request), but the earlier long models were so long - months - that another method of allocating credits was needed. Otherwise, users might get nothing if the model failed before the end and in any event would not get anything until the end, which might be rather too long for credit-minded participants to wait. So the "trickle" mechanism is used to allocate credits as the model progresses, even though run times are now much shorter, with a trickle uploaded at regular intervals (e.g. one month of simulated time): a fixed number of credits is then added per trickle.

In summary, ignore "pending" entirely.

[Edit: there is a "sticky" post on the subject here.]