We analyse thousands of lines from a csv using an LLM. The only thing that worked for us was to send each individual line and analyse it one by one.

I’m not sure if that would work in your use case, but you could classify each line into a value using an LLM then hard code the trends you are looking for.

For example if you’re analysing something like support tickets. Use an LLM to classify the sentiment, and you can plot the sentiment on a graph and see if it’s trending up or down.

you can use good old algorythms to search your special trends. just ask LLM how to code them. any algo you might need is somewhere inside of Donald Knuth's books.