Super interesting-this has expanded and clarified what was my apparently narrow understanding of the subjunctive mood, thinking that by its use in “irrealis” situations it was regulated only to ideas such as wishes, hopes, dreams, anxiety…etc.
Does this got anything to do with evidentiality? Evidentiality shows in a lot of languages, and I wonder if latin shows its evidentiality in the causal clause. If I witnessed an event could I use the indicative mood? "Grātiās eī ēgistī quia malōs tibi dedisset." If I witnessed the event of the third person giving the apples to the second person, could I say: "Grātiās eī ēgistī quia malōs tibi dederat"?
Your explanation on the subjunctive uses makes perfect sense, since these conjunctions plus the subjunctive were also used as an alternative for the accusative plus infinitive for indirect speech in later Latin. Instead of: audio illum esse discipulum bonum; It could be: audio quia ille sit discipulus bonus
