Thank you for your answer! I'll make good use of it, since copy pasting was unwieldy and I also had the same problems that are mentioned and resolved here [G3: Add Map Notes crashing]
EDIT: I found what I was looking for.
Through Near Infinity, indeed under Saves> [NameOfSave]>BALDUR.GAM, in the tab "Edit" are the strings associated with user entries in the journal. They are named Journal entry X in the "Attribute" column; the associated values are accessible with the "View/Edit" button at the bottom.
The text itself is stored in Saves> [NameOfSave]>BALDUR.SAV. Using the "Decompress" button at the bottom gives access to the function "View/Edit" for the DEFAULT.TOT file. Another use of "View/Edit" opens the table associated to the string, permitting copy past of the entry's text to whatever word processor you want, from the second column of the "Text" line. If no change is intended, no need to recompress the save. Each attribute equals an input by the user, not a journal entry, so if entries have been revised or written in multiple occurrences, they'll be divided into so much lines.