Python Text Processing Bug Fix

My Python data-processing script parses large batches of text and suddenly started throwing wrong results and occasional tracebacks. The trouble sits squarely in the text parsing section—no web-scraping or API layers are involved—so the focus is on hunting down logical errors in the existing codebase, tightening the parsing logic, and making sure edge cases stop slipping through.

You’ll receive the current .py files, sample input files, and the expected output format. I need you to isolate the bugs, patch them, and return a clean, well-commented script together with a short note explaining what changed and why. Quick turnaround is appreciated; once the fix passes my test set, the job is done.