This is intentional. You have to battle her at a higher difficulty than last time to receive a reward. Once you complete all her battles you don't get any more rewards.
Future higher difficulties are planned, presumably until you get all of her rewards, but for now there are only three? maybe four? I can't remember.
That's not right, you can get both of them without donating to the church. It's locked behind increasing your relationship with Lillian, which can be done by using all of her dialogue options, buying her holy water repeatedly, or just progressing the game.
I think the second (actually good) one is locked behind raising stats too, but not very far.
It's honestly not even just the quantity of text, but how that text is stored. There's no single master file with all the text in it, but a ton of different events stored seperately, each containing their own writing. Adding translation options would be great but it'd be a large coding task in addition to all the normal work that goes into making a translation.
