[I do apologise for the length but I’ve been feeling my way around here too much of late.]
Light dawns on marblehead! I’m such a dolt!
I went over these sections very carefully now and think I see my problem. This is a tricky section of the book, IMO. It’s very easy to misconstrue what is being said.
The four sections (§§ 201-204) introduce the perfect participle and the perfect passive tense.
First, we get the perfect passive participle and how to derive the perfect participle stem.
Second, we are told that the perfect participle stem forms the perfect, pluperfect and future perfect passive tenses.
Third, we are told that the perfect participle (but not the perfect passive tenses) may be used as an adjective and it agrees in gender, number, and case with the noun it modifies.
My trolley went off the track right here but I didn’t know it. In my head I had the only form so far presented, the perfect passive tenses, suddenly taking on the job of an adjective rather than the perfect participle.
Fourth, we are told how the perfect participle is declined (when used as an adjective) and conjugated in the passive form.
This is when I was asked to inflect the passive forms of a verb list. Now again, in my mind, the language is inflected by declining nouns and adjectives and conjugating verbs. Sematics? Yeah, I guess. sigh. I do get hung up on these sorts of things. sigh, sigh.
So first, I missed the point of the third section. I failed to see the perfect participle as an adjective. When you presented the usage (puellae amatae, puellis servatis, laudum amicum) I got thrown because I was looking for the auxiliary verb. Then you pointed out that as a verb it had damn well better have a nominative to agree with esse and at that point my trolley rolled over on its side and caught fire. So I also missed the “otherwise” part of the sentence.
But I believe I get it now.
adjective
Magister pueris fauturis multa dona dabit.
Magister pueris fauturis multa dona dat.
Magister pueris fauturis multa dona dabat.
Multa dona magistro pueris fauturis dantur.
“to the favored boys” is independent of the verb tense and
Multa dona magistro puero fauturo dantur.
Multa dona magistro puellae fauturae dantur.
faveo here is dependent only on puer/puella.
Passive verb
Pueri fauturi sunt magistro.
Pueri fauturi erant magistro.
Pueri fauturi erunt magistro.
Puellae fauturae sunt magistro.
And just to throw a bit more fuel on the fire:
Puer fauturus multa dona puellae pulchrae fauturae dat.
How’s that?