My try:
1) "My mother had decided that I have talent in language and literature, and opened my eyes to them." --- Grammatically wrong sentence.
2) "My mother had decided that I had talent in language and literature, and opened my eyes to them."-- This is okay.
The thing bothering me is 'I had talent' somehow feels like "I had it but now I don't", kind of idea, but in the context of the sentence structure this is not what it means, right? No, I can't make the same comment. I think such an information wasn't given in the sentece.