I'm using Lingva Latina: A College Companion, by Jeanne Marie Neumann to supplement LLPSI and in general I find it very useful (although there are a few minor typographical errors in it). I'm currently working through the review of Conditions (p241) and although I get the majority of it, there's one point I don't understand.
The text says that the Imperfect subjunctive represents the Present Unreal ("were... would") and gives the example
Sī iam hoc intellegerēs, certē patriam audīvissēs (i.e. Impf Subj / Plup Subj)
The translation given is "If you already understood this (but you clearly don’t), you certainly would be listening to your father (but you aren’t)"
The example for the Pluperfect Subjunctive (Past Unreal) is:
Sī iam tum hoc intellēxissēs, certē patrem audīvissēs (i.e. Plup Subj / Plup Subj)
with the translation "If you had already then understood this (but you clearly didn’t), you certainly would have listened to your father (but you didn’t)".
What I don't understand is why the pluperfect subjunctive is used in the second part of the first sentence (present unreal): why isn't it the imperfect subjunctive again, to show that the "not listening" is incomplete? Is the Pluperfect Subjunctive always used as the second part of present / past unreal constructions, regardless of completion / incompletion?