I can speak as to what is likely the cause for Hirogaru being missing as I have messed around with the bot's code a bit. Hirogaru is listed as a Winter 2023 show (ref). I doubt the instance of holo that is posting here has loaded the winter 2023 shows. That would likely cause a deluge of posts of old episodes/shows that would need cleaning up. I don't think it is very easy to just load one show and have it ignore the previously released episodes.

As for Otona, sometimes there are shows that the bot seems unable to find reliably. Another example from this season would be Tearmoon as it never made a thread yesterday for it. The bot works by scraping a bunch of streaming sites and a public torrent tracker for newly episode listings, so it can sometimes miss stuff if the formatting of a site changes or if there is an unexpected naming convention of a show.

Full disclosure, the reason I am somewhat familiar with how the bot works is that I have been tinkering around with the code to try to improve some of these things. The bot was originally made for r/anime almost a decade ago, so there are now much better apis available.

EDIT: I just loaded the winter shows on a local copy of holo and it was able to pick up Hirogaru, but still not Tearmoon or Otona.