Can you elaborate on what you mean?
I was assuming from this: "the export in the file always contains some errors or omissions, even if the previously prepared message input was ok." you meant you were having data analysis write to file.
Like you could say "Write me article outlines about these 5 topics: _______ and print it to a .txt file for me to download." (or whatever file format you want). It will give you a link to download. Then in your next prompt, say "Now do these topics: _______ and append to our text file" ... It will add to the first file and give you the link again. Continue in this way until you have all the outlines you want.
If it "forgets" the file (workspace environment times out), upload the most recent copy and prompt it again, telling it to append to the file you uploaded.
It's just another way of recording your output. It's not all that different from exporting the conversation history, except it won't be cluttered with the rest of your conversation, only the outlines you wanted.
I often work in this way while coding, passing files back and forth to code interpreter.
Edit: It's important to understand data analysis token limitations. ChatGPT won't respond to you with more than, say, 1,000 tokens worth of text. That's also the most it can directly write to file in one response. BUT, it can programmatically generate more than its token limit to a file. For instance, if you asked it to write for you on screen the numbers 1 through 1 million, it would never get there, out of tokens (it also might just refuse the request as wasteful.) But if you asked it to use python to fill a text file with the numbers one through a million, it could generate all one million lines, because they aren't being generated by GPT as tokens, they are being programmatically created by it running a script in its workspace.