Problem: Wiktionaries aims to offer for each meaning one definition but there are many ways to describe a meaning, many words - including local uses (i.e. an American-centered definition and an Indian-centered one for the same word) and very technical terms sometimes with more or less vulgarized explanations. A synthetic one is a solution, but more than one is better. Some alternative definitions from other dictionaries could be mentioned in the reference section but they are not accessible in Wiktionary and do not add any value to the entries.
Proposed solution: Wikisources contains a lot of dictionaries and we should use them to display more definitions. A dedicated transclusion of paragraphs from Wikisource in Wiktionaries could be a solution, by hand/bot or with an automatic harvesting of entries with a specific tagging in the dictionaries hosted in Wikisources. They could come from several Wikisources, to be display in several Wiktionaries. It could be a new tab next to "Article" and "Talk", named "Dictionaries" with definition for the same sequence of letters from dictionaries published in Wikisource. For French, I can imagine at least a dozen of definitions from as much dictionaries. For underdescribed languages with at least one source in Wikisource, it could be an interesting way to compare the source and how it evolve after its inclusion in Wiktionary.
Who would benefit: Readers wanting more than one definition, with different perspective.
More comments: Some dictionaries are already properly tagged; for the others, it could be a good opportunity to do it accordingly to TEI Lex0 guidelines, so that they can more easily be reused in open source projects. Also, to undermine a tendency when someone talk about Wiktionary: No, Wikidata Lexeme could not be of any help here. This issue is about content and not data or relation. Definitions are under CC BY-SA 3.0 in Wiktionary and in Wikisource dictionaries. This proposal is the same as this proposal in 2022 (24 supports) and this proposal in 2021 (supported by 40 people), this one in 2020 posted by DaraDaraDara (32 supports).