APIから「リアクション」情報を取得するにはどうすればよいですか？

[JammyDodger]

I think you can get them from this endpoint -

Discourse Likes API

Interestingly, if you have Reactions enabled you can use /discourse-reactions/posts/:post_id/reactions-users.json to get the created_at information for those (including for the reaction mapped to Like).