I was able to get it working locally by doing 2 things. First replacing all the "IsWrathClassic" checks with an "is wrath or cata" check and using it everywhere. Second by commenting out 3 spellids no longer in the game in the buff tracker list.

Fist for the wrath/cata checks. I did something like this:

local IsWrathOrCata = (WOW_PROJECT_ID == WOW_PROJECT_WRATH_CLASSIC) or (WOW_PROJECT_ID == WOW_PROJECT_CATACLYSM_CLASSIC)

Then I updated all usages to IsWrathOrCata instead of IsWrathClassic

Second, in ZPerl.lua, at about lines 2243, there are 3 spellids I commented out. Aspect of the Monkey, Seal of Command, and Seal of Wisdom.

After all of that it seemed to load and work well enough (initial testing)

Thanks for this, mine zperl is still very broken, showing blank name plates, I think Target and Target or Target etc.

Thanks @glajchs!
With your changes most of the errors are gone and the UI works mostly well!