Non solum forma sed etiam superbia reginae erat magna.
I do not know exactly what you're asking about it, but I get the impression you're seeing reginae as a plural when it is a singular genitive.
Not only the beauty but also the pride of the queen was great.
Diana eos inimicos Latonae delebit.
I am not in anyway an expert or fluent or even literate in Latin, but I do not see a problem with this, it seems to just carry more emphasis on inimicos than the key's example. Can any Latinist on here this up?
Mei finitimi consilio tuo non favebunt, quod bello student.
I also would have translated like how you did.
Mind you I know little Latin and the little help I offer I could be mistaken in.