Updated:
Test a typical page before processing a notebook. Joined letters can merge into the wrong word; margin notes and arrows can change the reading order. Check that crossed-out words were not included as final text. If a passage is ambiguous in the original, mark it as unresolved instead of guessing.
Copy corrected text when you need to rewrite a note. For a page image with a text layer, use searchable PDF export and test a distinctive word in the exported file. Export may resize or recompress the image; keep the original scan. To make a Word document, paste the text into Pages or Word and save there. For printed pages, see OCR on iPhone.
Try a representative page before relying on it. Joined letters, abbreviations and uneven spacing can produce wrong words or missing text. Legibility to a person does not guarantee correct OCR; compare the result with the source.
The page image and recognized text layer are different. OCR may have missed or misread that word, or the export may not include searchable text. Check the recognition result and export settings, then test the saved PDF in a compatible reader.
The public App Store listing advertises OCR in 14 languages. Handwriting recognition is narrower than printed-text recognition and varies by script, writing style, and image quality. Test representative pages and review important output against the original scan.
Text recognition runs on the iPhone and does not require uploading the page for OCR. Uploading, backup, or sharing through a cloud service requires the corresponding network connection.