What you place in the abstract fields of your own Zotero records should be what best serves your own needs.

Both within my personal use of Zotero and with the online academic bibliographic database that I curate; these "bullet point" key concepts are copied and placed within the abstract. Indeed, they are a summary of the aims, findings, and implications of the report (although they rarely do expose the study methods). Unless you plan to submit a detailed annotated bibliography (in a very specific format) to an eccentric university professor, what goes into the abstract is (within reason) up to you. Whether it is the author's narrative summary or the authors' bullet points seems an equivalency.

Incidentally, for my own Zotero records as well as with my public online literature database I often make changes to the authors' words. For example I clarify in an article about "football" if the article concerns "football [soccer]" or "[American] football". Similarly, there is a home childcare product that was commonly used in North America that is called a baby-walker or infant walker. Authors use these and more than 35 additional terms for these things. In my Zotero records I add the words "baby-walker" to the abstract in my Zotero record when authors use other English or non-English terms. (In the online database, the query thesaurus treats all of these terms as synonyms. A query for any synonym, if the searcher chooses, will return all records containing any of the terms chosen by the article's author.)