Comment scores are visible to the Algolia API after a period of time. Otherwise, the API returns a "null" for the points field. (example: https://hn.algolia.com/api/v1/items/2921983)
Oh, interesting. I stopped indexing HN comments after the points data became unavailable (it was still available through the Octopart guys' api, until Algolia took over). It looks like comment scores start showing up around the 30 day mark.
This is apparently unintended, as the official API has no points field. (example: https://hacker-news.firebaseio.com/v0/item/2921983.json?prin...)