I’ve been asking myself similar questions every time I’m organizing my collections… And in addition I have Energies from all languages. If only Energy cards had set symbols/numbers like the rest of the cards… 
I even have some Sun & Moon Energies without anything on them as indication… Not even a copyright date. That card pisses me off. 
Maybe @credits or @risingtrout can help answer some of your questions though, since they are two of the Energy collectors here on the forum. @credits also made this English Energy Card Checklist, which might already answers some of your questions?
Greetz,
Quuador