The instructions use the abbreviations TA and CA in various definitions; however, based on Chapter 4 in QFA and the CRSP/Compustat terms, it seems as though ACT (Current Assets - Total) works in place of both TA and CA. Am I understanding this correctly?

Compustat/CCM variables have their own naming styles, that's why you have to work with the data and current financial statements to make sure you are using the correct variable name. ACT I believe is total current assets; total assets would be another variable. (TA includes non-current assets.)